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991.
Paul C. D. Newton Mark Lieffering W. M. Saman D. Bowatte Shona C. Brock Chris L. Hunt Phil W. Theobald Des J. Ross 《Plant and Soil》2010,336(1-2):433-441
A decline in the availability of nitrogen (N) for plant growth (progressive nitrogen limitation or PNL) is a feedback that could constrain terrestrial ecosystem responses to elevated atmospheric CO2. Several long-term CO2 enrichment experiments have measured changes in plant and soil pools and fluxes consistent with PNL but evidence for PNL in grasslands is limited. In an 11 year Free Air CO2 Enrichment (FACE) experiment on grazed grassland we found the amount of N harvested in aboveground plant biomass was greater at elevated CO2 but declined over time to be indistinguishable from ambient after 5 years. Re-wetting after a major drought resulted in a large input of N from mineralisation and a return to a higher N harvested under elevated CO2 followed by a further decline. Over these two periods the amount of N in soil significantly increased at elevated CO2. Data from mesocosms introduced into the rings at intervals, and therefore having different lengths of exposure to CO2, showed plant N availability declined at elevated CO2 reaching a new equilibrium after 6 years of exposure. We conclude that the availability of N for plants in this grassland is dynamic but the underlying trend at elevated CO2 is for PNL. 相似文献
992.
Dong-Ha Oh Maheshi Dassanayake Jeffrey S. Haas Anna Kropornika Chris Wright Matilde Paino d’Urzo Hyewon Hong Shahjahan Ali Alvaro Hernandez Georgina M. Lambert Gunsu Inan David W. Galbraith Ray A. Bressan Dae-Jin Yun Jian-Kang Zhu John M. Cheeseman Hans J. Bohnert 《Plant physiology》2010,154(3):1040-1052
993.
Mark van de Wouw Theo van Hintum Chris Kik Rob van Treuren Bert Visser 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2010,120(6):1241-1252
In recent years, an increasing number of papers has been published on the genetic diversity trends in crop cultivars released
in the last century using a variety of molecular techniques. No clear general trends in diversity have emerged from these
studies. Meta analytical techniques, using a study weight adapted for use with diversity indices, were applied to analyze
these studies. In the meta analysis, 44 published papers were used, addressing diversity trends in released crop varieties
in the twentieth century for eight different field crops, wheat being the most represented. The meta analysis demonstrated
that overall in the long run no substantial reduction in the regional diversity of crop varieties released by plant breeders
has taken place. A significant reduction of 6% in diversity in the 1960s as compared with the diversity in the 1950s was observed.
Indications are that after the 1960s and 1970s breeders have been able to again increase the diversity in released varieties.
Thus, a gradual narrowing of the genetic base of the varieties released by breeders could not be observed. Separate analyses
for wheat and the group of other field crops and separate analyses on the basis of regions all showed similar trends in diversity. 相似文献
994.
995.
Background
An in silico analysis of the mitochondrial protein import apparatus from a variety of species; including Chlamydomonas reinhardtii, Chlorella variabilis, Ectocarpus siliculosus, Cyanidioschyzon merolae, Physcomitrella patens, Selaginella moellendorffii, Picea glauca, Oryza sativa and Arabidopsis thaliana was undertaken to determine if components differed within and between plant and non-plant species. 相似文献996.
Balamoody S Williams TG Waterton JC Bowes M Hodgson R Taylor CJ Hutchinson CE 《Arthritis research & therapy》2010,12(5):R202
Introduction
Cartilage thickness from MR images has been identified as a possible biomarker in knee osteoarthritis (OA) research. The ability to acquire MR data at multiple centers by using different vendors' scanners would facilitate patient recruitment and shorten the duration of OA trials. Several vendors manufacture 3T MR scanners, including Siemens, Philips Medical Systems, and GE Healthcare. This study investigates whether quantitative MR assessments of cartilage morphology are comparable between scanners of three different vendors. 相似文献997.
In the last fifteen years, rapid progress has been made in delineating the cellular response to DNA damage. The DNA damage response network is composed of a large number of proteins with different functions that detect and signal the presence of DNA damage in order to coordinate DNA repair with a variety of cellular processes, notably cell cycle progression. This signal, which radiates from the chromatin template, is driven primarily by phosphorylation events, mainly on serine and threonine residues. While we have accumulated detailed information about kinases and their substrates our understanding of the role of phosphatases in the DNA damage response is still preliminary. Identifying the phosphatases and their regulation will be instrumental to obtain a complete picture of the dynamics of the DNA damage response. Here we give an overview of the DNA damage response in mammalian cells and then review the data on the role of different phosphatases and discuss their biological relevance. 相似文献
998.
Leblanc DM Wood CM Fudge DS Wright PA 《Physiological and biochemical zoology : PBZ》2010,83(6):932-949
The euryhaline, amphibious mangrove killifish Kryptolebias marmoratus is known to survive weeks out of water in moist environments. We tested the hypothesis that the skin is a site of osmo- and ionoregulation in K. marmoratus. We predicted that under terrestrial conditions, gill and skin remodeling would result in an enhanced role for skin and a diminished role for the gills in osmo- and ionoregulation. Fish were exposed to water-either freshwater (FW, 1‰) or hypersaline water (saltwater [SW], 45‰)-or air over a moist surface of FW or SW for 9 d and then recovered in water. When fish were emersed for 9 d, (22)Na and (3)H-H(2)O were exchanged across the cutaneous surface. Homeostasis of whole-body Cl(-) and water levels but not of Na(+) levels was maintained over 9 d in air. In air-exposed fish, there was a significant increase in the size of skin ionocytes (in SW), a decrease in the number of skin mucous cells (in SW), and an increase in the gill interlamellar cell mass relative to those of fish in water. Gill ionocytes were mostly embedded away from the external surface in air-exposed fish, but the number and size of ionocytes increased (in FW). Interestingly, skin ionocytes formed distinct clusters of 20-30 cells. The estimated number of ionocytes over the whole skin surface was comparable to that in the gills. Overall, the findings support the hypothesis that the skin is a site of osmo- and ionoregulation in K. marmoratus in aquatic and terrestrial environments. Reversible cellular and morphological changes to the skin and gills during air exposure probably enhanced the cutaneous contribution to ion and water balance. 相似文献
999.
1000.
Beate Sander Jeffrey C. Kwong Chris T. Bauch Andreas Maetzel Allison McGeer Janet M. Raboud Murray Krahn 《PLoS medicine》2010,7(4)