全文获取类型
收费全文 | 4317篇 |
免费 | 482篇 |
国内免费 | 1篇 |
出版年
2022年 | 36篇 |
2021年 | 98篇 |
2020年 | 60篇 |
2019年 | 69篇 |
2018年 | 75篇 |
2017年 | 69篇 |
2016年 | 110篇 |
2015年 | 201篇 |
2014年 | 209篇 |
2013年 | 201篇 |
2012年 | 268篇 |
2011年 | 288篇 |
2010年 | 157篇 |
2009年 | 156篇 |
2008年 | 200篇 |
2007年 | 190篇 |
2006年 | 195篇 |
2005年 | 187篇 |
2004年 | 166篇 |
2003年 | 159篇 |
2002年 | 158篇 |
2001年 | 81篇 |
2000年 | 67篇 |
1999年 | 61篇 |
1998年 | 57篇 |
1997年 | 44篇 |
1996年 | 43篇 |
1995年 | 41篇 |
1994年 | 46篇 |
1993年 | 42篇 |
1992年 | 42篇 |
1991年 | 64篇 |
1990年 | 55篇 |
1989年 | 55篇 |
1988年 | 33篇 |
1987年 | 40篇 |
1986年 | 48篇 |
1985年 | 49篇 |
1984年 | 45篇 |
1983年 | 41篇 |
1982年 | 28篇 |
1981年 | 35篇 |
1980年 | 41篇 |
1979年 | 34篇 |
1978年 | 34篇 |
1977年 | 33篇 |
1975年 | 37篇 |
1974年 | 31篇 |
1973年 | 36篇 |
1972年 | 34篇 |
排序方式: 共有4800条查询结果,搜索用时 390 毫秒
991.
Expected Linkage Disequilibrium for a Neutral Locus Linked to a Chromosomal Arrangement 总被引:17,自引:11,他引:6
Curtis Strobeck 《Genetics》1983,103(3):545-555
The expected value of the squared linkage disequilibrium is derived for a neutral locus associated with a chromosomal arrangement that is maintained in the population by strong balancing selection. For a given value of recombination, the expected squared linkage disequilibrium is shown to decrease as the intensity of selection maintaining the arrangement increases. The transient behavior of the expected square linkage disequilibrium is also derived. This theory applies to loci that are closely linked to inversions in Drosophila species and to loci closely linked to the differential segments of the translocation complexes in ring-forming species of Oenothera. In both cases the strong linkage disequilibria that have been observed in natural populations can be explained by random drift. 相似文献
992.
G D Virca G S Salvesen J Travis 《Hoppe-Seyler's Zeitschrift für physiologische Chemie》1983,364(9):1297-1302
The sites of cleavage in the "bait region" of human alpha 2-macroglobulin made by both neutrophil elastase and cathepsin G, as the first step in their inactivation by this inhibitor, have been identified. These positions are at a valylhistidyl bond for elastase and a phenylalanyl-tyrosyl bond for cathepsin G. All of the proteinases tested so far, including those utilized in this study, are cleaving within a twenty-seven aminoacid peptide sequence occurring between two proline residues. It is suggested that this area represents the outer limits of the "bait region" loop. 相似文献
993.
A protein with a molecular weight of 60,000 (60K) constitutes approximately 20% of the envelope protein of Azotobacter vinelandii. This protein was removed from cells and purified from other proteins by a simple washing procedure that had no effect on cell viability. Anti-60K antiserum blocked azotophage A-22 adsorption and agglutinated both vegetative cells and cysts; ferritin-conjugated antibodies used in indirect labeling studies bound uniformly to the periphery of vegetative cells. We conclude that 60K is present on the outer surface of vegetative cells and cysts. The protein is similar to the surface protein alpha of Acinetobacter ssp. in molecular weight, reassociation characteristics, and high ratio of acidic to basic amino acids. We propose that 60K forms a layer external to the outer membrane of A. vinelandii. 相似文献
994.
995.
The rate of destruction of the far red absorbing form of phytochrome(Pfr) in green or etiolated cuttings of Vigna radiata was slowerin the presence of malformin than in its absence. Malforminhad no effect on the accumulation of total phytochrome in thedark, or on the reaccumulation of phytochrome after destructionin red light. The amount of photoconversion of the red absorbingform of phytochrome (Pr) to Pfr or Pfr to Pr by given dosesof red or far red radiation was slightly but consistently lessin malformin-treated cuttings of V. radiata than in controls.Malformin had no effect on the rate of destruction or photoconversionof phytochrome in etiolated shoots of Avena sativa. The decreasein destruction rate of Pfr by malformin in V. radiata may contributeto the inhibition of dark abscission by malformin after lighttreatment. (Received October 3, 1979; ) 相似文献
996.
K2S2O8, applied to the basal end of cuttings of Vigna radiatastimulated leaf abscission in the light or dark. Because inhibitionof leaf sbscission in the dark by IAA was completely abolishedby K2S2O8, and IAA decreased stimulation of abscission by K2S2O8,destruction of IAA in the cuttings by K2S2O8 is indicated. K2S2O8had no effect on leaf abscission when applied as a foliar sprayor when roots of undisturbed seedlings were treated. When appliedproximally or distally to leafless explants, K2S2O8 inhibitedpetiole abscission, and neither IAA nor ethylene had an effecton the inhibition. Although K2S2O8 destroyed IAA in vitro, ithad no effect on abscission inhibitors in macerates of Vignaleaves and corn roots, nor did it destroy the biological activityof IAA added to such macerates. Substances liberated by macerationmay interfere with the ability of K2S2O8 to destroy IAA. (Received May 2, 1981; Accepted August 24, 1981) 相似文献
997.
Characterization and quantitation of concanavalin a binding by plasma membrane enriched fractions from soybean root 总被引:4,自引:4,他引:0
下载免费PDF全文
![点击此处可从《Plant physiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The binding of concanavalin A (Con A) to soybean root membranes in plasma membrane enriched fractions (recovered from the 34/45% interface of simplified discontinuous sucrose density gradients) was studied using a radiochemical assay employing tritiated (3H)-Con A. The effect of lectin concentration, time, and membrane protein concentration on the specific binding of 3H-Con A by the membranes was evaluated. Kinetic analyses showed that Con A will react with membranes in that fraction in a characteristic and predictable manner. The parameters for an optimal and standard binding assay were established. Maximal binding occurred with Con A concentrations in the range of 8 to 16% of the total membrane protein with incubation times greater than 40 min at 22 C. Approximately 1015 molecules of 3H-Con A were bound per microgram of membrane protein at saturation. Binding was reversible. Greater than 92% of the total Con A bound at saturation was released by addition of α-methyl mannoside. 相似文献
998.
Evidence for an Inactivating System of Nitrate Reductase in Hordeum vulgare L. during Darkness That Requires Protein Synthesis 总被引:20,自引:14,他引:6
下载免费PDF全文
![点击此处可从《Plant physiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The disappearance of nitrate reductase activity in leaves of Hordeum vulgare L. during darkness was inhibited by cycloheximide, actinomycin D, and low temperature. Thus, protein synthesis was probably required for the disappearance of nitrate reductase in the dark. Since chloramphenicol did not affect the rate of loss of activity, the degradation or inactivation apparently required protein synthesis by the cytoplasmic ribosomal system. Consistent with this observation, nitrate reductase is also reportedly located in the cytoplasm. Thus, the amount of nitrate reductase activity present in leaves of barley may be controlled by a balance between activating and inactivating systems. 相似文献
999.
Curtis RW 《Plant physiology》1969,44(9):1368-1370
1000.
Action Spectrum of the Photoinduced Sexual Stage in the Fungus Nectria haematococca Berk. and Br. var cucurbitae (Snyder and Hansen) Dingley 总被引:1,自引:1,他引:0
下载免费PDF全文
![点击此处可从《Plant physiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Curtis CR 《Plant physiology》1972,49(2):235-239
An action spectrum was determined for the photoinduced formation of perithecia in a homothallic strain of Nectria haematococca Berk. and Br. var. cucurbitae (Snyder and Hansen) Dingley. Dose-response curves for perithecial formation were obtained from 340 to 510 nanometers at 10-nanometer intervals. Radiation longer than 510 nanometers was not effective for inducing perithecial formation. The action spectrum indicated peaks of activity near 360, 440, and 480 nanometers with shoulders near 420 and 460 nanometers. Minima occurred near 350 nanometers, 390 to 410 nanometers, and 470 nanometers. The general shape of this action spectrum appears to be similar to those obtained for many different near ultraviolet-blue-sensitive organisms in which a flavoprotein molecule was postulated to be the photoreceptor. 相似文献