全文获取类型
收费全文 | 21530篇 |
免费 | 1122篇 |
国内免费 | 27篇 |
出版年
2023年 | 164篇 |
2022年 | 369篇 |
2021年 | 777篇 |
2020年 | 446篇 |
2019年 | 487篇 |
2018年 | 708篇 |
2017年 | 651篇 |
2016年 | 867篇 |
2015年 | 996篇 |
2014年 | 1284篇 |
2013年 | 1719篇 |
2012年 | 1830篇 |
2011年 | 1631篇 |
2010年 | 964篇 |
2009年 | 838篇 |
2008年 | 1008篇 |
2007年 | 975篇 |
2006年 | 832篇 |
2005年 | 762篇 |
2004年 | 614篇 |
2003年 | 526篇 |
2002年 | 476篇 |
2001年 | 369篇 |
2000年 | 329篇 |
1999年 | 288篇 |
1998年 | 134篇 |
1997年 | 91篇 |
1996年 | 108篇 |
1995年 | 89篇 |
1994年 | 75篇 |
1993年 | 71篇 |
1992年 | 174篇 |
1991年 | 174篇 |
1990年 | 144篇 |
1989年 | 112篇 |
1988年 | 157篇 |
1987年 | 137篇 |
1986年 | 120篇 |
1985年 | 111篇 |
1984年 | 113篇 |
1983年 | 73篇 |
1982年 | 58篇 |
1981年 | 72篇 |
1980年 | 60篇 |
1979年 | 84篇 |
1977年 | 62篇 |
1976年 | 51篇 |
1975年 | 49篇 |
1973年 | 49篇 |
1972年 | 57篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
22.
23.
24.
25.
R. N. Sinha 《Entomologia Experimentalis et Applicata》1965,8(4):309-313
Two stored-product insects were reared on 23 species of seed-borne fungi and 1 species of actinomycete at 33°C and 75% R.H. Cryptolestes ferrugineus (Stephens) completed development on 10 species of fungi; the shortest development period, 22 days, was on Trichothecium roseum Lk. and the longest, 34 days, on Fusarium moniliforme Sheld. Oryzaephilus mercator (Fauvel) completed development on 18 species of fungi; the shortest developmental period, 21 days, was on Mucor sphaerosporus Hagem, and the longest, 40 days, on Chaetomium funicola Cooke. None developed on Streptomyces griseus (Krainsky) Waksman & Henrici.
Contribution No. 154. 相似文献
Zusammenfassung Zwei Vorratsschädlinge wurden bei 33° und 75% rel. Luftfeuchtigkeit auf 23 Pilzarten und einer Actinomycetenart aufgezogen, die sich auf Samen entwickeln. Cryptolestes ferrugineus vollendete seine Entwicklung auf 10 Pilzarten in 22 bis 34 Tagen; die kürzeste Entwicklungsdauer, 22 Tage, zeigte sich auf Trichothecium roseum Lk. und die längste, 34 Tage, auf Fusarium moniliforme Sheld. Oryzaephilus mercator entwickelte sich auf 18 Pilzarten in 21 bis 40 Tagen. Die kürzeste Entwicklungsperiode ergab sich auf Mucor sphaerosporus Hagem., die längste auf Chaetomium funicola Cooke. Keine Entwicklung trat auf Streptomyces griseus (Krainsky) Waksman & Henrici ein.
Contribution No. 154. 相似文献
26.
Siddhartha Kumar Bhaumik Manoj Kumar Singh Subir Karmakar Tripti De 《Glycoconjugate journal》2009,26(6):663-673
As compared to cutaneous leishmaniasis, vaccination against visceral leishmaniasis (VL) has received limited attention. In
this study, we demonstrate for the first time that an UDP-Galactose: N-acetylglucosamine β 1–4 galactosyltransferase (GenBank Accession No. EF159943) expressing attenuated LD clonal population (A-LD) is able to confer protection against the experimental challenge with the virulent LD AG83 parasite. A-LD was also effective in established leishmania infection. The vaccinated animals showed both cell mediated
(in vitro T-cell proliferation, and DTH response) and humoral responses (Th1 type). These results demonstrate the potential of the
attenuated clones as an immunotherapeutic and immunoprophylactic agent against visceral leishmaniasis. 相似文献
27.
Experimental evidence suggests that proteins adsorbed to hydrophobic surfaces at low coverages are stabilized relative to the bulk. For larger coverages, proteins unfold and form β-sheets. We performed computer simulations on model proteins and found that: 1), For weakly adsorbing surfaces, unfolded conformations lose more entropy upon adsorption than folded ones. 2), The melting temperature, both in the bulk and at surfaces, decreases with increasing protein concentration because of favorable interprotein interactions. 3), Proteins in the bulk show large unfolding free energy barriers; this barrier decreases at stronger adsorbing surfaces. We conjecture that typical experimental temperatures appear to be below the bulk melting temperature for a single protein, but above the melting temperature for concentrated protein solutions. Purely thermodynamic factors then explain protein stabilization on adsorption at low concentrations. However, both thermodynamic and kinetic factors are important at higher concentrations. Thus, proteins in the bulk do not denature with increasing concentration due to large kinetic barriers, even though the aggregated state is thermodynamically preferred. However, they readily unfold upon adsorption, with the surface acting as a heterogeneous catalyst. The thermal behavior of proteins adsorbed to hydrophobic surfaces thus appears to follow behavior independent of their chemical specificity. 相似文献
28.
Eriocaulon raipurense (Eriocaulaceae) is described and illustrated as a new species from Madhya Pradesh, India. The species is closely allied to E. hamiltonianum but differs in the size and apex of involucral bancts, white-pilose nature of floral bracts and colour of female petals. 相似文献
29.