全文获取类型
| 收费全文 | 41757篇 |
| 免费 | 372篇 |
专业分类
| 林业 | 1857篇 |
| 农学 | 1265篇 |
| 基础科学 | 247篇 |
| 6716篇 | |
| 综合类 | 4323篇 |
| 农作物 | 1536篇 |
| 水产渔业 | 2092篇 |
| 畜牧兽医 | 20897篇 |
| 园艺 | 481篇 |
| 植物保护 | 2715篇 |
出版年
| 2021年 | 435篇 |
| 2020年 | 479篇 |
| 2019年 | 463篇 |
| 2018年 | 1000篇 |
| 2017年 | 1099篇 |
| 2016年 | 984篇 |
| 2015年 | 686篇 |
| 2014年 | 949篇 |
| 2013年 | 2210篇 |
| 2012年 | 1556篇 |
| 2011年 | 1710篇 |
| 2010年 | 1127篇 |
| 2009年 | 1075篇 |
| 2008年 | 1568篇 |
| 2007年 | 1494篇 |
| 2006年 | 1252篇 |
| 2005年 | 1118篇 |
| 2004年 | 1048篇 |
| 2003年 | 969篇 |
| 2002年 | 850篇 |
| 2001年 | 962篇 |
| 2000年 | 941篇 |
| 1999年 | 732篇 |
| 1998年 | 283篇 |
| 1997年 | 260篇 |
| 1995年 | 292篇 |
| 1992年 | 501篇 |
| 1991年 | 499篇 |
| 1990年 | 518篇 |
| 1989年 | 540篇 |
| 1988年 | 438篇 |
| 1987年 | 444篇 |
| 1986年 | 468篇 |
| 1985年 | 414篇 |
| 1984年 | 394篇 |
| 1983年 | 356篇 |
| 1979年 | 568篇 |
| 1978年 | 393篇 |
| 1977年 | 429篇 |
| 1976年 | 513篇 |
| 1975年 | 525篇 |
| 1974年 | 604篇 |
| 1973年 | 534篇 |
| 1972年 | 514篇 |
| 1971年 | 433篇 |
| 1970年 | 396篇 |
| 1969年 | 464篇 |
| 1968年 | 464篇 |
| 1967年 | 473篇 |
| 1966年 | 462篇 |
排序方式： 共有10000条查询结果，搜索用时 15 毫秒
101.
Summary Leptospira interrogansserotypes pomonaand icterohaemorrhagiaewere isolated from the kidneys of Rattus norvegicustrapped on pomonainfected piggeries.The isolation of pomonafrom one of 111cultured kidneys, although of interest, strongly suggests that this rat does not play an important part in the epidemiology of infection by this serotype.
Kidney tubular degeneration, focal mononuclear infiltrations and fibroplasia are morphological traces which remain after an attack of leptospirosis. The high percentage (48.6)of these lesions found in the rat kidneys examined does not seem to be related to serotype pomonabut to icterohaemorrhagiae.The importance of this last serotype in swine in the Cauca Valley has yet to be assessed.
Leptospirosis En Colombia: Aislamiento DeLeptospira SPP. De Riñones De Ratas Pardas (Rattus Norvegicus) Atrapadas En Porquerizas Infectadas
Resumen Se aislóLeptospira interrogans serotipospomona eicterohaemorrhagiae de riñones deRattus norvegicus atrapadas en porquerizas infectadas porpomona. El aislamiento depomona de 1/111 riñones cultivados, aunque de interés, sugiere que esta rata no desempeña parte importante en la epidemiología de las infecciones por este serotipo.Degeneración tubular renal, infiltración mononuclear focal y fibroplasia son huellas morfológicas que quedan después de un ataque de leptospirosis. El alto porcentaje (48.6) de estas lesiones encontradas en los riñones de las ratas examinadas no parece estar relacionado con el serotipopomona sino con elicterohaemorrhagiae. La importancia de este último seroptipo en cerdos en el Valle del Cauca no se ha evaluado todavía.
Leptospiroses En Colombie: Isolement DeLeptospira SPP. De Reins De Rats Bruns (Rattus Norvegicus) Captures Dans Des Porcheries
Résumé Les sérotypespomona eticterohaemorrhagiae deLeptospira interrogans ont été isolés de reins deRattus norvegicus capturés dans des porcheries infectées de (pomona?). L'isolement depomona sur une seule des 111 cultures de rein effectuées, bien qu'interessant, suggère fortement que ce rat ne joue pas un rôle important dans l'épidémiologie de l'infection par ce sérotype.La dégénerescence tubulaire des reins, des infiltrations ponctuelles par des monocucléaires et l'aspect fibreux constituent les traces morphologiques qui demeurent après une attaque de leptospirose. Le pourcentage élevé (48,6) de ces lésions trouvées dans les les reins des rats examinés semble être plus en rapport avec le sérotypeicterohaemorrhagiae qu'avec le sérotypepomona. L'importance du sérotypeicterohaemorrhagiae chez le porc de la Cauca Valley est encore à vérifier.相似文献
102.
Cultivation of sunflower (Helianthus annuus L.) is strongly affected by Sclerotinia sclerotiorum. To identify new sources of genetic diversity for sunflower breeding 25 sunflower inbred lines were analysed using eight Amplified Fragment Length Polymorphism (AFLP) primer combinations and their genetic similarities (GS) were estimated. Data were used to develop a Unweighted Pair Group Method using Arithmetic Averages (UPGMA) dendrogram. GS values of 0.58‐0.98 were observed but with no separate groupings dependant on oil quality. The inbred lines were screened for their reaction to inoculation with Sclerotinia sclerotiorum (Lib.) de Bary. Sunflower heads were artificially inoculated with S. sclerotiorum in three environments. Head infection was monitored after 1 week (lesion length) and 2 weeks (head rot). The F5 generation of a cross between a resistant (SWS‐B‐04) and a susceptible inbred line (SWS‐B‐01) was also tested for sclerotinia reaction across three environments. Significant differences in sclerotinia resistance, moderate heritabilities and a high correlation between the two assessments were observed. Inbred lines with a high level of resistance could be identified. These lines can be used for further breeding to improve sunflower sclerotinia resistance and to develop superior new hybrids. 相似文献
103.
Émilie L. Couture Beatriz P. Monteiro Jessica Aymen Eric Troncy Paulo V. Steagall 《Veterinary anaesthesia and analgesia》2017,44(3):676-683
Objectives
To validate a thermal threshold (TT) nociceptive model in bearded dragons (Pogona vitticeps) and to document TT changes after administration of morphine.Study design
A two-part randomized, blinded, controlled, experimental study.Animals
Five adult bearded dragons (242–396 g).Methods
A TT device delivered a ramped nociceptive stimulus (0.6 °C second?1) to the medial thigh until a response (leg kick/escape behavior) was observed or maximum (cut-off) temperature of 62 °C was reached. In phase I, period 1, six TT readings were determined at 20 minute intervals for evaluation of repeatability. Two of these readings were randomly assigned to be sham to assess specificity of the behavioral response. The same experiment was repeated 2 weeks later (period 2) to test reproducibility. In phase II, animals were administered either intramuscular morphine (10 mg kg?1) or saline 0.9%. TTs (maximum 68 °C) were determined before and 2, 4, 8, 12 and 24 hours after treatment administration. Data were analyzed using one-way anova (temporal changes and repeatability) and paired t tests (reproducibility and treatment comparisons) using Bonferroni correction (p < 0.05).Results
Mean TT values were 57.4 ± 3.8 °C and 57.3 ± 4.3 °C for periods 1 and 2, respectively. Data were repeatable within each period (p = 0.83 and p = 0.07, respectively). Reproducibility between periods was remarkable (p = 0.86). False-positive responses during sham testing were 10%. TTs were significantly increased after morphine administration at 2, 4 and 8 hours compared with baseline, and at 2 and 4 hours compared with saline 0.9%. The highest TT was 67.7 ± 0.7 °C at 4 hours after morphine administration.Conclusions and clinical relevance
Testing was repeatable, reproducible and well tolerated in bearded dragons. TT nociceptive testing detected morphine administration and may be suitable for studying opioid regimens in bearded dragons. 相似文献104.
Agroforestry Systems - Nutrient buildup in the soil caused by increased animal manure and fertilizer use in agricultural and forestry practices may increase the potential for their loss from the... 相似文献
105.
106.
I. V. Ivanov 《Eurasian Soil Science》2007,40(1):103-107
107.
R. N. WHITE BSc BVetMed CertVA Diplomate ECVS J. V. DAVIES BVetMed PhD DVR Diplomate ECVS S. P. GREGORY BVetMed PhD DVR 《Veterinary surgery : VS》1996,25(6):503-510
Vaginourethroplasty was performed in six bitches with infiltrative, obstructive urethral disease. The initial clinical signs included dysuria, hematuria, pollakiuria, and stranguria. Diagnosis was based on the clinical signs, plain radiography and contrast vagino-urethrogram examination, and urethral biopsy. Five dogs were diagnosed as having urethral neoplasia; the sixth dog had granulomatous urethritis. In all six dogs, up to 50% of the urethra and the urethral tubercle were resected to ensure adequate surgical margins. One dog was euthanatized 4 months after surgery for recurrence of a transitional cell carcinoma at the surgical site. Long-term resolution of the problem (minimum of 12 months) was achieved in the other five dogs. The frequency of serious complications, including urinary incontinence and ascending lower urinary tract infections, was low. 相似文献
108.
109.
Alizadeh M Rassoulian GR Karimzadeh J Hosseini-Naveh V Farazmand H 《Pakistan journal of biological sciences: PJBS》2011,14(24):1090-1099
Plutella xylostella (L.) (Lep: Plutellidae), is a destructive pest of brassicaceous crops in the world. Cotesia vestalis (Haliday) is one of most important biological control agents of P. xylostella in the world and Iran. Both of P. xylostella and C. vestalis biology were carried out in laboratory condition. Results showed that development time of immature stages of P. xylostella including egg, Instar I, Instar II, Instar III, Instar IV, prepupa, pupa were 2.39 +/- 0.17, 2.18 +/- 0.17, 2.06 +/- 0.28, 2.14 +/- 0.14, 2.54 +/- 0.12, 0.40 +/- 0.12 and 4.23 +/- 0.23 days, respectively. Longevity of female and male were 28.26 +/- 0.05 and 30.22 +/- 0.05 days. By dissecting the parasitized larvae, the egg incubation period of C. vestalis was recorded 1.73 +/- 0.06 days. In long-term oviposition trials, females laid eggs on P. xylostella larvae for up to 10 days. Larval development of the parasitoid in host only required 6.47 days: the first instar larva required 3.25 +/- 0.047 days; the second instar larva needed 2.78 +/- 0.1 days and the third instar larvae exited the host and pupated in, 0.4 +/- 0.07 days. Prepupal and pupal period of wasp were 1.9 +/- 0.06 and 2.13 +/- 0.09 day, respectively. Unmated female and male longevity of wasp were 16.83 +/- 0.37, 16.25 +/- 0.17 and sex ratio is male-biased. When a mixed group and isolated of instars were presented for parasitoid, the 2nd and 3rd instar larvae were so preferred and the 4th instar was less attractive for selection. In choice experiment, the percentage parasitism of 2nd, 3rd and 4th instars was 78.58, 69.94 and 4.36%, respectively. The rapid oviposition rate, short life duration and high percentage parasitism increases parasitoid potential for suppression of host population. Present results suggest that C. vestalis has considerable potential as a biological control agent for P. xylostella. 相似文献
110.
M. Anusuya Devi L. V. Venkataraman 《Plant foods for human nutrition (Dordrecht, Netherlands)》1983,33(4):287-297
The protein quality of algaeSpirulina platensis was evaluated biochemically in adult albino rats by serum protein regeneration studies. Rats depleted for 12 days were repleted for 15 days with diets containing 10% protein derived from algae, methionine supplemented algae, or casein. On protein depletion, the activity of the hepatic enzymes, succinic dehydrogenase and alanine aminotransferase, were lowered while the activity of alkaline phosphatase increased. Protein repletion with algal and casein diets resulted in an increased activity of succinic dehydrogenase and alanine amino transferase and a decrease in alkaline phosphatase activity. However, the levels of these three enzymes were lower with the algal than with the casein diets. Algal diets regenerated serum protein effectively though to a slightly lesser extent than casein. 相似文献