全文获取类型
收费全文 | 5646篇 |
免费 | 496篇 |
国内免费 | 1篇 |
出版年
2023年 | 18篇 |
2022年 | 36篇 |
2021年 | 92篇 |
2020年 | 54篇 |
2019年 | 71篇 |
2018年 | 82篇 |
2017年 | 87篇 |
2016年 | 140篇 |
2015年 | 193篇 |
2014年 | 258篇 |
2013年 | 317篇 |
2012年 | 359篇 |
2011年 | 357篇 |
2010年 | 272篇 |
2009年 | 218篇 |
2008年 | 313篇 |
2007年 | 307篇 |
2006年 | 258篇 |
2005年 | 265篇 |
2004年 | 298篇 |
2003年 | 281篇 |
2002年 | 258篇 |
2001年 | 121篇 |
2000年 | 87篇 |
1999年 | 96篇 |
1998年 | 99篇 |
1997年 | 63篇 |
1996年 | 52篇 |
1995年 | 42篇 |
1994年 | 43篇 |
1993年 | 54篇 |
1992年 | 81篇 |
1991年 | 72篇 |
1990年 | 66篇 |
1989年 | 59篇 |
1988年 | 47篇 |
1987年 | 45篇 |
1986年 | 28篇 |
1985年 | 29篇 |
1984年 | 41篇 |
1983年 | 35篇 |
1982年 | 30篇 |
1981年 | 21篇 |
1980年 | 21篇 |
1979年 | 22篇 |
1978年 | 22篇 |
1977年 | 18篇 |
1974年 | 21篇 |
1973年 | 20篇 |
1972年 | 19篇 |
排序方式: 共有6143条查询结果,搜索用时 15 毫秒
1.
Shira Weingarten-Gabbay Susan Klaeger Siranush Sarkizova Leah R. Pearlman Da-Yuan Chen Kathleen M.E. Gallagher Matthew R. Bauer Hannah B. Taylor W. Augustine Dunn Christina Tarr John Sidney Suzanna Rachimi Hasahn L. Conway Katelin Katsis Yuntong Wang Del Leistritz-Edwards Melissa R. Durkin Christopher H. Tomkins-Tinch Pardis C. Sabeti 《Cell》2021,184(15):3962-3980.e17
2.
Rachael V. Gallagher Lesley Hughes Michelle R. Leishman Peter D. Wilson 《Biological invasions》2010,12(12):4049-4063
Potential interactions between climate change and exotic plant invasions may affect areas of high conservation value, such
as land set aside for the protection of endangered species or ecological communities. We investigated this issue in eastern
Australia using species distribution models for five exotic vines under climate regimes for 2020 and 2050. We examined how
projected changes in the distribution of climatically suitable habitat may coincide with the remaining remnants of an endangered
ecological community—littoral rainforests—in this region. The number of known infestations of each weed in tropical, subtropical
and temperate areas was used to assess the likelihood of further expansion into areas projected to provide suitable habitat
under future conditions. Littoral rainforest reserves were consistently predicted to provide bioclimatically suitable habitat
for the five vines examined under both current and future climate scenarios. We explore the consequences and potential strategies
for managing exotic plant invasions in these protected areas in the coming decades. 相似文献
3.
J.N. Beresford J.A. Gallagher M. Gowen M. Couch J. Poser D.D. Wood R.G.G. Russell 《Biochimica et Biophysica Acta (BBA)/General Subjects》1984,801(1):58-65
Cultural adherent human mononuclear cells produce factor(s) which stimulate the release of calcium from new-born mouse calvaria in organ culture. This stimulation of bone resorption is accompanied by an inhibition of the incorporation of [3H]proline into collagen which is independent of increased prostaglandin production by the bone. When human osteoblast-like cells are treated with conditioned medium from human mononuclear cells, collagen accounts for a decreased proportion of the protein synthesised. This effect on matrix synthesis is not accompanied by an inhibitory action of the monocyte-conditioned medium preparations on net cell proliferation. In human osteoblast-like cell cultures, partially purified human interleukin 1 also inhibits the production of the bone-specific protein osteocalcin in a dose-dependent fashion. These observations are consistent with the hypothesis that products of human monocytes similar to, or identical with, human interleukin 1 may be important regulators of bone metabolism and may contribute to the bone loss seen in diseases such as chronic rheumatoid arthritis. 相似文献
4.
5.
6.
7.
Denis Williams 《BMJ (Clinical research ed.)》1964,2(5424):1554-1557
8.
9.
M P Shiaris A C Rex G W Pettibone K Keay P McManus M A Rex J Ebersole E Gallagher 《Applied and environmental microbiology》1987,53(8):1756-1761
The impact of a sewage point source on the bacterial densities in an intertidal mud flat in Boston Harbor, Mass., was investigated. The area, Savin Hill Cove, acts as a receiving basin for a combined storm and sewage outlet (CSO). Preliminary examination of sediments and overlying water at high tide demonstrated that fecal coliforms were present in sediments at abundances 2 to 4 orders of magnitude higher than in the overlying water column. The following bacterial counts were determined from sediments along a sampling transect extending 460 m from the CSO: total bacteria by epifluorescent microscopy, heterotrophic bacteria by plate counts on nutrient-rich and nutrient-poor media, fecal coliforms and enterococci by membrane filtration, and Vibrio parahaemolyticus by a most-probable-number technique with a resuscitation step. Median sediment grain size, average tidal exposure, carbon/nitrogen ratio, and total organic carbon were also measured. All bacterial indices, except for V. parahaemolyticus, declined significantly with distance from the outfall. Multiple regression analysis indicated that tidal exposure (low tides) may affect densities of total bacteria. Fecal coliforms and enterococci were still present in appreciable numbers in sediments as far as 460 m away from the CSO. In contrast, V. parahaemolyticus densities did not correlate with the other bacterial counts nor with any of the environmental parameters examined. These results indicate that intertidal sediments which adjoin point sources of pollution are severely contaminated and should be considered as potentially hazardous reservoirs of sewage-borne diseases. 相似文献
10.
C Bailly J P Catteau N Helbecque J L Bernier R Houssin C Denis J P Hénichart 《Journal of inorganic biochemistry》1987,31(3):211-220
A model incorporating the metal chelating moiety of bleomycin and an anilinoacridine ring able to intercalate in DNA has been synthesized. The copper(II) complex of that molecule has been studied using circular dichroism and electron spin resonance by comparison with bleomycin. The introduction of the anilinoacridine ring involves a modification in the geometry of the complex. A distortion of the square-pyramidal form (type II complex) gives rise to a type I complex in which the metallic atom is drawn out of the plane of the four square-planar ligands and displaced slightly towards the fifth ligand. 相似文献