全文获取类型
收费全文 | 5907篇 |
免费 | 558篇 |
国内免费 | 1篇 |
专业分类
6466篇 |
出版年
2023年 | 32篇 |
2022年 | 74篇 |
2021年 | 148篇 |
2020年 | 70篇 |
2019年 | 107篇 |
2018年 | 118篇 |
2017年 | 108篇 |
2016年 | 166篇 |
2015年 | 300篇 |
2014年 | 297篇 |
2013年 | 394篇 |
2012年 | 554篇 |
2011年 | 485篇 |
2010年 | 336篇 |
2009年 | 294篇 |
2008年 | 364篇 |
2007年 | 409篇 |
2006年 | 387篇 |
2005年 | 324篇 |
2004年 | 310篇 |
2003年 | 302篇 |
2002年 | 228篇 |
2001年 | 50篇 |
2000年 | 45篇 |
1999年 | 45篇 |
1998年 | 63篇 |
1997年 | 23篇 |
1996年 | 37篇 |
1995年 | 28篇 |
1994年 | 24篇 |
1993年 | 30篇 |
1992年 | 25篇 |
1991年 | 15篇 |
1990年 | 18篇 |
1989年 | 26篇 |
1988年 | 22篇 |
1987年 | 14篇 |
1986年 | 9篇 |
1985年 | 9篇 |
1984年 | 15篇 |
1982年 | 14篇 |
1980年 | 12篇 |
1979年 | 10篇 |
1978年 | 9篇 |
1977年 | 14篇 |
1976年 | 8篇 |
1975年 | 9篇 |
1974年 | 16篇 |
1973年 | 12篇 |
1972年 | 8篇 |
排序方式: 共有6466条查询结果,搜索用时 0 毫秒
101.
Oliver A.H. Jones Lee A. Walker Jeremy K. Nicholson Richard F. Shore Julian L. Griffin 《Comparative biochemistry and physiology. Part D, Genomics & proteomics》2007,2(4):316-321
Proton (1H) Nuclear Magnetic Resonance (NMR) spectroscopy was used to investigate the biochemical response of bank voles and wood mice (two wild rodent species frequently found on metal-contaminated sites) to chronic cadmium (Cd) insult. Similar effects, in terms of both metabolic changes (consistent with cellular acidosis) and induced metallothionin (MT) production were observed in all animals. These changes appeared to be an adaptation of the liver to toxic insult rather than onset of a toxic effect, and, in common with previous studies, were more marked in bank voles than wood mice. This may have reflected the greater Cd intake and assimilation of the former but was not explained by differences in concentrations of free (non MT-bound) Cd; concentrations of which were negligible in both voles and mice. Responses to Cd insult were detected in both species even though their bodies contained cadmium concentrations well below the World Health Organisation critical renal concentration of 200 μg/g dry mass. 相似文献
102.
Exceptionally preserved North American Paleogene metatherians: adaptations and discovery of a major gap in the opossum fossil record 总被引:1,自引:0,他引:1
Sánchez-Villagra M Ladevèze S Horovitz I Argot C Hooker JJ Macrini TE Martin T Moore-Fay S de Muizon C Schmelzle T Asher RJ 《Biology letters》2007,3(3):318-322
A major gap in our knowledge of the evolution of marsupial mammals concerns the Paleogene of the northern continents, a critical time and place to link the early history of metatherians in Asia and North America with the more recent diversification in South America and Australia. We studied new exceptionally well-preserved partial skeletons of the Early Oligocene fossil Herpetotherium from the White River Formation in Wyoming, which allowed us to test the relationships of this taxon and examine its adaptations. Herpetotheriidae, with a fossil record extending from the Cretaceous to the Miocene, has traditionally been allied with opossums (Didelphidae) based on fragmentary material, mainly dentitions. Analysis of the new material reveals that several aspects of the cranial and postcranial anatomy, some of which suggests a terrestrial lifestyle, distinguish Herpetotherium from opossums. We found that Herpetotherium is the sister group to the crown group Marsupialia and is not a stem didelphid. Combination of the new palaeontological data with molecular divergence estimates, suggests the presence of a long undocumented gap in the fossil record of opossums extending some 45Myr from the Early Miocene to the Cretaceous. 相似文献
103.
Kaori Kurashima-Ito Kayano Moromisato Kaoru Nishimura Markus Wälchli Jeremy R. H. Tame Yutaka Ito 《Biomolecular NMR assignments》2007,1(1):37-39
Salmonella typhimurium OppA is the periplasmic oligopeptide-binding protein. Backbone resonances of OppA(D419N) on its own were assigned for ∼90%
of residues. Missing residues are localised around the ligand-binding site, suggesting conformational flexibility in the unliganded
state. 相似文献
104.
105.
A flexible process monitoring method was applied to industrial pilot plant cell culture data for the purpose of fault detection and diagnosis. Data from 23 batches, 20 normal operating conditions (NOC) and three abnormal, were available. A principal component analysis (PCA) model was constructed from 19 NOC batches, and the remaining NOC batch was used for model validation. Subsequently, the model was used to successfully detect (both offline and online) abnormal process conditions and to diagnose the root causes. This research demonstrates that data from a relatively small number of batches (approximately 20) can still be used to monitor for a wide range of process faults. 相似文献
106.
107.
108.
Christopher W. Schmidt Ashley Remy Rebecca Van Sessen John Willman Kristin Krueger Rachel Scott Patrick Mahoney Jeremy Beach Jaqueline McKinley Ruggero D'Anastasio Laura Chiu Michele Buzon J. Rocco De Gregory Susan Sheridan Jacqueline Eng James Watson Haagen Klaus Pedro Da-Gloria Jeremy Wilson Abigail Stone Paul Sereno Jessica Droke Rose Perash Christopher Stojanowski Nicholas Herrmann 《American journal of physical anthropology》2019,169(2):207-226
109.
Shah Mansi Nel Jeremy Almansouri Abdulrahman Van Duin David Gerber David A. 《Mycopathologia》2019,184(1):155-158
Mycopathologia - Hepatic mucormycosis is a disease caused by a ubiquitous fungus which is especially important in patients with hematologic malignancies. We present a case of an adult patient with... 相似文献
110.
Jason E. Chung Hannah R. Joo Jiang Lan Fan Daniel F. Liu Alex H. Barnett Supin Chen Charlotte Geaghan-Breiner Mattias P. Karlsson Magnus Karlsson Kye Y. Lee Hexin Liang Jeremy F. Magland Jeanine A. Pebbles Angela C. Tooker Leslie F. Greengard Vanessa M. Tolosa Loren M. Frank 《Neuron》2019,101(1):21-31.e5