全文获取类型
收费全文 | 1077篇 |
免费 | 64篇 |
国内免费 | 9篇 |
专业分类
林业 | 67篇 |
农学 | 72篇 |
基础科学 | 27篇 |
411篇 | |
综合类 | 103篇 |
农作物 | 95篇 |
水产渔业 | 62篇 |
畜牧兽医 | 184篇 |
园艺 | 28篇 |
植物保护 | 101篇 |
出版年
2023年 | 16篇 |
2022年 | 43篇 |
2021年 | 71篇 |
2020年 | 70篇 |
2019年 | 92篇 |
2018年 | 115篇 |
2017年 | 105篇 |
2016年 | 78篇 |
2015年 | 38篇 |
2014年 | 46篇 |
2013年 | 130篇 |
2012年 | 56篇 |
2011年 | 70篇 |
2010年 | 40篇 |
2009年 | 25篇 |
2008年 | 36篇 |
2007年 | 26篇 |
2006年 | 25篇 |
2005年 | 11篇 |
2004年 | 6篇 |
2003年 | 8篇 |
2002年 | 5篇 |
2000年 | 3篇 |
1999年 | 1篇 |
1998年 | 4篇 |
1997年 | 4篇 |
1996年 | 3篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有1150条查询结果,搜索用时 31 毫秒
91.
Growth,yield and water productivity of dry direct seeded rice and transplanted aromatic rice under different irrigation management regimes 下载免费PDF全文
Muhammad ISHFAQ Nadeem AKBAR shakeel Ahmed ANJUM Muhammad ANWAR-UL-HAQ 《农业科学学报》2020,19(11):2656-2673
Sustainability of traditionally cultivated rice in the rice-wheat cropping zone (RWCZ) of Pakistan is dwindling due to the high cost of production, declining water resources and escalating labour availability. Thus, farmers and researchers are compelled to find promising alternatives to traditional transplanted rice (TPR). A field study was conducted in Punjab, Pakistan, in 2017 and 2018 to explore the trade-offs between water saving and paddy yield, water productivity and economics of two aromatic rice varieties under dry direct seeded rice (DDSR) and TPR. The experiment was comprised of three irrigation regimes on the basis of soil moisture tension (SMT) viz., continuous flooded (>−10 kPa SMT), alternate wetting and drying (AWD) (−20 kPa SMT) and aerobic rice (−40 kPa SMT), maintained under TPR and DDSR systems. Two aromatic rice verities: Basmati-515 and Chenab Basmati-2016 were used during both years of study. In both years, DDSR produced higher yields (13–18%) and reduced the total water inputs (8–12%) in comparison to TPR. In comparison to traditional continuous flooded (CF), AWD under DDSR reduced total water input by 27–29% and improved the leaf area index (LAI), tillering, yield (7–9%), and water productivity (44–50%). The performance of AWD with regard to water savings and increased productivity was much higher in DDSR system as compared to AWD in TPR system. Cultivation of DDSR with aerobic irrigation improved water savings (49–55%) and water productivity (22–30%) at the expense of paddy yield reduction (36–39%) and spikelet sterility. With regard to variety, the highest paddy yield (6.6 and 6.7 t ha−1) was recorded in DDSR using Chenab Basmati-2016 under AWD irrigation threshold that attributed to high tiller density and LAI. The economic analysis showed DDSR as more beneficial rice establishment method than TPR with a high benefit-cost ratio (BCR) when the crop was irrigated with AWD irrigation threshold. Our results highlighted that with the use of short duration varieties, DDSR cultivation in conjunction with AWD irrigation can be more beneficial for higher productivity and crop yield. 相似文献
92.
Five crop straws(wheat, rice, maize, oil-rape, and cotton) were first steam-exploded for 2 min at 210°C, 2.5 MPa and then pyrolyzed at 500°C for 2 h. Steam explosion(SE) induced 47–95% and 5–16% reduction of hemicellulose and cellulose, respectively, in the crop straws. The biochars derived from SE-treated feedstocks had a lower specific surface area(SSA) and pore volume, compared to those from pristine feedstocks, with one exception that SE enhanced SSA of oil-rape straw biochar by approximately 16 times. After SE, biochars had significant higher anion exchange capacity(AEC)(6.88–11.44 cmol kg~(–1)) and point of zero net charges(PZNC)(pH 3.61–5.32) values. It can thus be speculated that these biochars may have higher potential for anions adsorption. In addition, oil-rape straw might be suitable to SE pretreatment for preparing biochar as a soil amendment and sorbent as well. Further work is required for testing its application in soil. 相似文献
93.
Shahid Iqbal Shahzad M. A. Basra Irfan Afzal Abdul Wahid Muhammad S. Saddiq Muhammad B. Hafeez Sven‐Erik Jacobsen 《Journal of Agronomy and Crop Science》2019,205(1):13-21
Quinoa is recently introduced to Pakistan as a salt‐tolerant crop of high nutritional value. Open field trials were conducted to evaluate its performance on normal and salinity/sodicity‐degraded lands at two locations of different salinity/sodicity levels, S1 (UAF Farm, Normal Soil), S2 (Paroka Farm UAF, saline sodic), S3 (SSRI Farm, normal) and S4 (SSRI Farm, saline sodic) during 2013–2014. Two genotypes (Q‐2 and Q‐7) were grown in lines and were allowed to grow till maturity under RCBD split‐plot arrangement. Maximum seed yield (3,062 kg/ha) was achieved by Q‐7 at normal field (S1) soil which was statistically similar with yield of same genotype obtained from salt‐affected field S2 (2,870 kg/ha). Furthermore, low yield was seen from both genotypes from both S3 and S4 as compared to S1 and S2. Q‐7 was best under all four conditions. Minimum yield was recorded from Q‐2 (1,587 kg/ha) at S4. Q‐7 had higher SOD, proline, phenolic and K+ contents, and lower Na+ content in leaves as compared to Q‐2. High levels of antioxidants and K+/Na+ of Q‐7 helped to withstand salt stress and might be the cause of higher yields under both normal and salt‐affected soils. Seed quality (mineral and protein) did not decrease considerably under salt‐affected soils even improved seed K+, Mg2+ and Mn2+. 相似文献
94.
In plants, male sterility (MS) is a specific breeding target trait. With the advancements in agriculture, utilization of heterosis breeding in hybrid production through MS lines has become the main breeding tool of various cross‐pollinated and even self‐pollinated crops. Soybean is an essential source of oil and protein; however, the low yield is a major factor limiting its development. Soybean MS mainly comprises cytoplasmic‐nuclear MS and nuclear/genic MS (NMS/GMS), which can effectively utilize heterosis to improve soybean yield. This review outlines the recent research progress on the development of new genetically MS lines, exploring the underlying molecular mechanism of MS, identification and cloning of MS and fertility restoration genes, and the application of MS lines. We further discussed and prospected the future developmental scenario direction of the soybean MS, based on the previous studies of other crops sterility system. Moreover, this review also provides comprehensive information for better application of MS to soybean breeding programme. 相似文献
95.
Muhammad Omer Aijaz Sajjad Haider Fahad S. Al-Mubaddel Rawaiz Khan Adnan Haider Abdulaziz Abdullah Alghyamah Waheed A. Almasry Mohammad Sherjeel Javed Khan Muhammad Javid Wajahat Ur Rehman 《Fibers and Polymers》2017,18(4):611-618
The present study is focused on studying the swelling kinetics, thermal and aqueous stabilities, and determination of various forms of water in the chitosan (CS) and polyacrylonitrile (PAN) blend and semi-interpenetrating polymer network (sIPN). CS/PAN blend hydrogel films were prepared by solution casting technique. The blend film with optimum swelling properties was selected for the synthesis of sIPN. CS in the blend was crosslinked with the vapors of Glutaraldehyde (GTA) to prepare sIPN. The fabricated CS/PAN blend and sIPN hydrogels films were characterized with Fourier transform infrared (FTIR), thermal gravimetric analysis (TGA) and field emission scanning electron microscope (FESEM). The kinetics of swelling, bound and unbound waters and aqueous stability were determined experimentally. FESEM showed good miscibility between CS and PAN, FTIR showed no chemical interaction between CS and PAN; however, it did show a doublet for the sIPN, TGA showed improved thermal stability and swelling kinetic followed second order kinetics. The degree of swelling of the sIPN hydrogels samples at room temperature varied from ~2200 % (with a fair degree of stability (~30 %)) to ~1000 % (with high degree of aqueous stability (43 %)) with increase in the crosslinking time. The calculated unbound water (WUB) max., for the blend was 52.3 % whereas for the bound (WB) the max., was 41.9 %. However, for sIPN hydrogel films, the WUB water decreased (max. 21.0 %) where as the WB increased (max. 52.0 %). The decrease in WUB and increase in the WB is attributed to the formation of a compact structure and increase in the contact area between the water and polymers in sIPN hydrogels due to the induction of new water contacting point in these hydrogel films, respectively. 相似文献
96.
Agroforestry practices of farming communities are investigated in southern Punjab province, Pakistan. It is hypothesized that rural people of this areas are more inclined than elsewhere in the province to practice agroforestry due to greater profitability than cropping. A landholder survey revealed that the majority of farmers are inclined to plant trees on their land. Low accessibility of institutional credit is a constraint for both agroforestry farmers (AF) and non-agroforestry farmers. However, among AF respondents only 24% were found to need credit for agroforestry practice, as against nearly 76% for crop production. Mostly farmers were found to have positive perceptions regarding agroforestry practice, because they understand the multiple benefits from growing trees, compared with cropping where farmers face various constraints, including poor access to credit, natural hazards, and little support from local authorities. Further, effort to sensitize farmers that growing trees has multiple benefits compared to only cultivation of field crops can bring about change in farmer’s perceptions and attitudes in the Indus River basin, resulting in motivation for agroforestry adoption. 相似文献
97.
Genome-wide association analysis for stripe rust resistance in spring wheat(Triticum aestivum L.) germplasm 下载免费PDF全文
Sher MUHAMMAD Muhammad SAJJAD Sultan Habibullah KHAN Muhammad SHAHID Muhammad ZUBAIR Faisal Saeed AWAN Azeem Iqbal KHAN Muhammad Salman MUBARAK Ayesha TAHIR Muhammad Umer Rumana KEYANI Muhammad Inam AFZAL Irfan MANZOOR Javed Iqbal WATTOO Aziz-ur REHMAN 《农业科学学报》2020,19(8):2035-2043
Stripe rust is a continuous threat to wheat crop all over the world. It causes considerable yield losses in wheat crop every year. Continuous deployment of adult plant resistance(APR) genes in newly developing wheat cultivars is the most judicious strategy to combat this disease. Herein, we dissected the genetics underpinning stripe rust resistance in Pakistani wheat germplasm. An association panel of 94 spring wheat genotypes was phenotyped for two years to score the infestation of stripe rust on each accession and was scanned with 203 polymorphic SSRs. Based on D' measure, linkage disequilibrium(LD) exhibited between loci distant up to 45 c M. Marker-trait associations(MTAs) were determined using mixed linear model(MLM). Total 31 quantitative trait loci(QTLs) were observed on all 21 wheat chromosomes. Twelve QTLs were newly discovered as well as 19 QTLs and 35 previously reported Yr genes were validated in Pakistani wheat germplasm. The major QTLs were QYr.uaf.2 AL and QYr.uaf.3 BS(PVE, 11.9%). Dissection of genes from the newly observed QTLs can provide new APR genes to improve genetic resources for APR resistance in wheat crop. 相似文献
98.
Riaz Aayesha Yousaf Arfan Moaeen-ud-Din Muhammad Shah Muhammad Ali Abdullah Zainab Tayyaba Masood Sadia Akhter Naeem Ali Adnan 《Veterinary research communications》2019,43(4):197-202
Veterinary Research Communications - Avian polyomavirus (APV) infection, also called as budgerigar fledgling disease (BFD) causes various health problems in many psittacine species which may cause... 相似文献
99.
Ali Murtaza Waqas Ahmad Tariq Sohail Muhammad Irfan‐ur‐Rehman Khan Imran Mohsin Muhammad Shahzad Mujahid Hussain Muhammad Zahid Tahir Muhammad Ijaz 《Reproduction in domestic animals》2019,54(3):545-550
This study compares the factors associated with variable interval to oestrus and ovulation between early versus late ovulating goats following PGF2α administration. The time of ovulation in Beetal goats (n = 38) was monitored through transrectal ultrasound at every 6 hr following a single dose of PGF2α (experiment 1). Variations in oestrus and ovulation times were further explored through the changes in follicular dynamics, endocrine profiles and behaviour in another set of goats (n = 13) following single PGF2α given randomly during the luteal phase (experiment 2). The ovulation time varied between 60 and 96 hr, and 57% of ovulations occurred by 72 hr following PGF2α (experiment 1). Accordingly, the goats (n = 13) in the second experiment were retrospectively divided either into early and/or late ovulating, that is, ≤72 and/or ≥84 hr following PGF2α. The onset of oestrus, peak estradiol‐17β concentration and LH surge after PGF2α was first observed in early than late ovulating goats (p < 0.05). The goats ovulating early had larger follicle and smaller CL in diameter at the time of PGF2α administration than those ovulating late (5.4 ± 0.2 vs. 4.3 ± 0.2 mm and 10 ± 0.6 vs. 11.8 ± 0.3 mm, respectively; p < 0.05). Likewise, plasma progesterone concentration tended to be lower (p = 0.087) in early than late ovulating goats. In conclusion, the size of dominant follicle and CL at the time of PGF2a determines the interval to ovulation following a single dose of PGF2a during the luteal phase. 相似文献
100.
Hambali Idris Umar Abdullah Faez Firdaus Jesse Bin Bhutto K. R. Mohd Azmi M. L. Wahid A. H. Zakaria Z. Odhah M. N. Arsalan M. Muhammad N. A. Jefri M. N. 《Tropical animal health and production》2019,51(4):781-789
Tropical Animal Health and Production - Mastitis is the inflammation of the mammary gland due to microbial infiltration causing a reduced mammary function. This study aims at developing a vaccine... 相似文献