全文获取类型
收费全文 | 18477篇 |
免费 | 1570篇 |
国内免费 | 3篇 |
专业分类
20050篇 |
出版年
2023年 | 105篇 |
2022年 | 240篇 |
2021年 | 429篇 |
2020年 | 242篇 |
2019年 | 304篇 |
2018年 | 385篇 |
2017年 | 356篇 |
2016年 | 572篇 |
2015年 | 938篇 |
2014年 | 1057篇 |
2013年 | 1230篇 |
2012年 | 1751篇 |
2011年 | 1583篇 |
2010年 | 950篇 |
2009年 | 844篇 |
2008年 | 1186篇 |
2007年 | 1209篇 |
2006年 | 999篇 |
2005年 | 975篇 |
2004年 | 821篇 |
2003年 | 801篇 |
2002年 | 779篇 |
2001年 | 182篇 |
2000年 | 148篇 |
1999年 | 172篇 |
1998年 | 183篇 |
1997年 | 109篇 |
1996年 | 98篇 |
1995年 | 98篇 |
1994年 | 91篇 |
1993年 | 91篇 |
1992年 | 104篇 |
1991年 | 85篇 |
1990年 | 93篇 |
1989年 | 63篇 |
1988年 | 69篇 |
1987年 | 54篇 |
1986年 | 67篇 |
1985年 | 47篇 |
1984年 | 53篇 |
1983年 | 39篇 |
1982年 | 25篇 |
1981年 | 28篇 |
1980年 | 29篇 |
1979年 | 29篇 |
1978年 | 31篇 |
1976年 | 24篇 |
1974年 | 21篇 |
1971年 | 21篇 |
1969年 | 23篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
The ability to metabolically label proteins with 35S-methionine is critical for the analysis of protein synthesis and turnover. Despite the importance of this approach, however, efficient labeling of proteins in vivo is often limited by a low number of available methionine residues, or by deleterious side-effects associated with protein overexpression. To overcome these limitations, we have created a methionine-rich variant of the widely used HA tag, called HAM, for use with ectopically expressed proteins. Here we describe the development of a series of vectors, and corresponding antisera, for the expression and detection of HAM-tagged proteins in mammalian cells. We show that the HAM tag dramatically improves the sensitivity of 35S-methionine labeling, and permits the analysis of Myc oncoprotein turnover even when HAM-tagged Myc is expressed at levels comparable to that of the endogenous protein. Because of the improved sensitivity provided by the HAM tag, the vectors and antisera described here should be useful for the analysis of protein synthesis and destruction at physiological levels of protein expression. 相似文献
3.
4.
5.
The direct binding of porcine pancreatic phospholipase A2 and its zymogen to 1,2-bis(heptanylcarbamoyl)-rac-glycerol 3-sulfate was studied by optical detection of triplet-state magnetic resonance spectroscopy in zero applied magnetic field. The zero-field splittings of the single Trp3 residue undergo significant changes upon binding of phospholipase A2 to lipid. Shifts in zero-field splittings, characterized mainly by a reduction of the E parameter from 1.215 to 1.144 GHz, point to large changes in the Trp3 local environment which accompany the complexing of phospholipase A2 with lipid. This may be attributed to Stark effects caused by the binding of a charged group near Trp3 in the enzyme-lipid complex. The cofactor, Ca2+, which is strongly bound to the enzyme active site, has an influence on the bonding, as reflected by smaller zero-field splitting shifts. A relatively small change in the Trp environment was observed for the interaction of the zymogen with lipid. 相似文献
6.
Andreas Barth 《BBA》2007,1767(9):1073-1101
This review discusses the application of infrared spectroscopy to the study of proteins. The focus is on the mid-infrared spectral region and the study of protein reactions by reaction-induced infrared difference spectroscopy. 相似文献
7.
Summary In the initial phase of the geotropical reaction of the Chara rhizoid the growth difference postulated by Sievers (1967c) between the physically upper, slightly subapical flank and the lower one is demonstrated. In horizontal exposure the growth of the extreme cell apex is continued, while the growth of the lower flank is inhibited and that of the upper one is promoted. In the end phase the cell apex shows a damped oscillation until it finally reaches the vertical growth direction. The statoliths follow the oscillating growth of the cell tip from one flank to the opposite one until they are statistically equally redistributed in their normal position.—In vertical exposure under reduced turgor pressure the statoliths fall down into the extreme cell apex, where they inhibit the growth of this part of the cell wall, while the subapical wall grows transversally.—It is concluded that the statoliths inhibit the growth of the cell wall area which they cover.—The physical phase of the reaction chain, the susception, is the gravity-induced downward displacement of the statoliths. The physiological phase starts with the diversion of the acropetal transport of the Golgi vesicles to the upper part of the cell, which is caused by the block of statoliths (perception). The greater rate of vesicle incorporation into the upper flank in comparison to the lower one causes the subapical growth difference which results in the curvature (reaction).—In the case of the Chara rhizoid Golgi- and statolith-apparatus function as a self-regulating cellular system.
Herrn Prof. Dr. Dr. h. c. Kurt Mothes zum 70. Geburtstag. 相似文献
Herrn Prof. Dr. Dr. h. c. Kurt Mothes zum 70. Geburtstag. 相似文献
8.
Laura Cernat Cristina Blaj Rene Jackstadt Lydia Brandl Jutta Engel Heiko Hermeking Andreas Jung Thomas Kirchner David Horst 《PloS one》2014,9(8)
Colonic crypts are stereotypical structures with distinct stem cell, proliferating, and differentiating compartments. Colorectal cancers derive from colonic crypt epithelia but, in contrast, form morphologically disarrayed glands. In this study, we investigated to which extent colorectal cancers phenocopy colonic crypt architecture and thus preserve structural organization of the normal intestinal epithelium. A subset of colon cancers showed crypt-like compartments with high WNT activity and nuclear β-Catenin at the leading tumor edge, adjacent proliferation, and enhanced Cytokeratin 20 expression in most differentiated tumor epithelia of the tumor center. This architecture strongly depended on growth conditions, and was fully reproducible in mouse xenografts of cultured and primary colon cancer cells. Full crypt-like organization was associated with low tumor grade and was an independent prognostic marker of better survival in a collection of 221 colorectal cancers. Our findings suggest that full activation of preserved intestinal morphogenetic programs in colon cancer requires in vivo growth environments. Furthermore, crypt-like architecture was linked with less aggressive tumor biology, and may be useful to improve current colon cancer grading schemes. 相似文献
9.
Katharina Bork Johannes Karstensen Martin Visbeck Andreas Zimmermann 《Ocean Development & International Law》2013,44(3):298-328
This article analyzes the legal status of unmanned instruments (particularly, floats and gliders) for observation purposes in the ocean environment. These new kinds of instruments are being deployed by the thousands into the oceans, not the least as part of the Argo Project of the International Oceanographic Commission. Their uncontrolled drifting has raised legal questions, especially when such instruments enter waters subject to the jurisdiction of foreign states. The authors argue that the current international legal framework is insufficient to address the pertinent issues, and that a new legal regime is needed. 相似文献
10.