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81.
木材构造和生体节律的1/f型涨落谱 总被引:1,自引:0,他引:1
在综合现代木质环境学研究成果的基础上,就自然界中普遍存在着的涨落现象、涨落的分类、各种涨落谱的特征等做了一般性的说明。集中讨论了木材构造的涨落谱及生体节律的涨落谱特征,并就两者之间存在的共同点,即两者之间的相关性做了浅显说明,回答了为什么自古以来人们喜爱生物材料——木材及木材纹理构造这一问题的根本原因。 相似文献
82.
乳源木莲管形容器育苗技术研究 总被引:1,自引:0,他引:1
通过对乳源木莲进行不同基质配比、容器规格、营养液施肥、苗高生长节律等管形容器育苗试验,结果表明,培育乳源木莲管形容器苗的理想基质材料应以泥炭、鸡粪泥炭、蛭石、珍珠岩等轻型基质为主,容器规格大小与培育期限和苗龄是密切相关的,采用N、P、K配比3:2:1、1:1:1两种配方营养液配方施肥可促进苗木生长发育和根系成团,提高苗木综合质量;乳源木莲管形容器苗的年高生长进程呈现慢—快—慢的“S”形节律,存在着明显的速生期,在该期内的苗高生长量最大。 相似文献
83.
低成本纤维素酶的生产是酶法转化纤维质生物量为酒精的关键。尽管已有很多有关纤维素酶的研究报告,但底物的预处理对固态发酵过程中pH值和产酶的影响很少见诸于报道。作者研究了在固态发酵过程中,里氏木霉在未处理和经挤压处理的麦糟培养基上pH值的变化。经单螺杆和双螺杆挤压的麦糟,其纤维的结晶度变化较小。单螺杆挤压撕开了纤维结构,而双螺杆破坏并摧毁了纤维细胞的细胞壁,同时麦糟的颗粒也变得很小。两种经挤压处理的麦糟均有利于菌体的生长,并提高了产酶。以单螺杆挤压处理的麦糟为培养基时,最高FPA酶活力为182.8IU/g纤维素。 相似文献
84.
《Wood material science & engineering》2007,2(2):83-89
To study the effect of grain angle on the adhesive bond strength in wood, three-part Norway spruce wood specimens were bonded and tested in tension. The two axially orientated outer parts of the specimens were joined with the middle part by means of three adhesives typically used for load-bearing constructions, i.e. one-component polyurethane (PUR), melamine-urea-formaldehyde (MUF) and phenol-resorcinol-formaldehyde (PRF). The grain angle of the middle part was varied from 0° (end grain to end grain) to 90° (flat grain to end grain) in incremental steps of 10°. In general, PRF- and MUF-bonded samples exhibited highest tensile strength at end grain to end grain orientation of the three parts, while specimens bonded with PUR showed only 25% of the strength measured for PRF and MUF, respectively. At high grain angles (90°) all specimens showed similar strength values in the range of 30% of maximum strength of MUF- and PRF-bonded specimens. To explain the changing strength levels at different grain angle a composite failure criterion was applied. 相似文献
85.
The effects of shoot size and differences in budburst phenology ofQuercus serrata trees on the spatial patterns of galls were investigated for two cynipid species: the sexual generation ofAndricus moriokae and the agamic generation ofAphelonyx glanduliferae. There were marked differences in budburst phenology, but these did not affect the gall density on the tree. The galls of
both cynipids showed a contagious distribution in their respective trees, but different abundance patterns under high gall
density. The mean number of galls ofA. glanduliferae over a shoot size range was positively correlated with shoot size. More galls ofA. moriokae appeared on larger shoots on trees on which many buds had started growing before oviposition by the agamic adults. In the
case of a tree on which a few buds had burst by the time of oviposition, the mean numbers ofA. moriokae galls on shoots of particular size ranges depended on the frequency of shoots in the size class. These results suggest that,
although these cynipids prefer to attack larger shoots within a host tree, they may exhibit plasticity in their preference
in response to changes in budburst phenology of the host plant relative to the time of oviposition. 相似文献
86.
Influence of Ammoniacal Copper Quaternary treatments on mechanical properties of blue-stained Lodgepole Pine wood 总被引:1,自引:0,他引:1
Three concentrations (2.8%, 2.0%, 1.2%) of Ammoniacal Copper Quaternary (ACQ) was selected to treat Lodgepole pine wood for evaluating ACQ treatment on mechanical properties of blue-stained wood. The bending modules of elasticity (MOE), modules of rupture (MOR), toughness and shearing strength parallel to grain on tangential surface, are tested according to the criteria GB1927-1943-91. Non-treated sample were also tested according to the same procedure. The results showed that the three groups specimen impregnated by different concentrations of ACQ solution met the AWPA standard 2003 of America (UC4A 6.4g/cm^3). There were significant difference of toughness between treated wood and non-treated wood (p=0.01), but there were no statistically significant differences among three concentrations in terms of toughness, and toughness of treated wood was approximately 20% lower than non-treated. MOR, MOE as well as sheafing strength parallel to grain were found to be not significantly different between treated wood and non-treated one, and there were no statistically significant difference among three concentrations of ACQ too. Toughness, MOR, MOE and sheafing strength parallel to grain increased with decrease of concentration of ACQ, but they were hardly affected by ACQ preservatives. 相似文献
87.
R. G. Muschler 《Agroforestry Systems》2001,51(2):131-139
Quality is an important attribute of coffee. Therefore it is important to understand the effect of overstory trees not only on the environment and long-term coffee production, but also on the quality of coffee grown underneath the trees. This study compared coffee quality of Coffea arabica L. vars. Caturra and Catimor 5175 under different levels of shade in a low-elevation, sub-optimal environment for coffee in Costa Rica. Fruit weight and bean size increased significantly when shade intensity was increased from 0% to more than 80% under unpruned Erythrina poeppigiana. While large beans (diameter > 6.7 mm) accounted for 49 and 43% of the coffee from unshaded Caturra and Catimor, respectively, these proportions increased to 69 and 72% under dense permanent shade. This suggested a stronger shade benefit for Catimor than for Caturra. The conversion percentages from fresh-weight coffee fruits to dry-weight green coffee for export were not affected by the treatments. A blind tasting experiment showed consistent shade-induced improvements in appearance of green and roasted coffee as well as in acidity and body of the brew for both varieties. The effect of shade on aroma of the brew was neutral for Caturra and slightly negative for Catimor. It is hypothesized that, in the sub-optimal (low-altitude) coffee-zone studied, shade promotes slower and more balanced filling and uniform ripening of berries, thus yielding a better-quality product than unshaded coffee plants. Shade experiments along environmental gradients should help to validate this conjecture and its relative importance in different coffee-zones. 相似文献
88.
松香酰胺在中性造纸施胶中的应用 总被引:2,自引:0,他引:2
利用松香与异腈酸的酰经反应在100-150℃下合成了三个松香酰胺,并应用它们到中性造纸松香乳酸,PH4-8的抄造试验表明这些松香衍生物在这个PH范围内具有高的施胶效果。松香酰结构与酰胺化度对施胶效果有很大的影响。 相似文献
89.
90.
Application of cationic polymer prepared from sulfuric acid lignin as a retention aid for usual rosin sizes to neutral papermaking 总被引:3,自引:0,他引:3
Yasuyuki?MatsushitaEmail author Ayuko?Iwatsuki Seiichi?Yasuda 《Journal of Wood Science》2004,50(6):540-544
Cationic polymers that acted as the retention aids for usual rosin sizes in neutral papermaking were prepared from sulfuric acid lignin (SAL), one type of acid lignin. To convert SAL to the cationic polymer (MP-SAL), SAL was phenolated and then treated by the Mannich reaction to introduce the amino groups. In the MP-SAL single system, MP-SAL exhibited high sizing effectiveness in neutral papermaking with the rosin emulsion size. However, MP-SAL showed no sizing effectiveness when soap rosin size was used. MP-SAL showed increased sizing effectiveness as the pK
a of the introduced amino group increased. From this and comparison of the sizing degrees of MP-SAL and polyethylenimine, which possesses a linear structure, it was suggested that the sizing effectiveness was not only affected by the charge density and molecular weight, but also by the basicity of the introduced amino groups and the molecular structure of the retention aid. In the alum–MP-SAL dual system, alum and MP-SAL synergistically enhanced the sizing effectiveness in the rosin emulsion sizing at neutral pH. In turn, this allowed a decrease in the MP-SAL dosage and resulted in a small decrease in brightness.Part of this report was presented at the 48th Lignin Symposium, October 2003, Fukui 相似文献