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81.
Schönswetter P Lachmayer M Lettner C Prehsler D Rechnitzer S Reich DS Sonnleitner M Wagner I Hülber K Schneeweiss GM Trávnícek P Suda J 《Journal of plant research》2007,120(6):721-725
We explored the fine-scale distribution of cytotypes of the mountain plant Senecio carniolicus along an altitudinal transect in the Eastern Alps. Cytotypes showed a statistically significant altitudinal segregation with
diploids exclusively found in the upper part of the transect, whereas diploids and hexaploids co-occurred in the lower range.
Analysis of accompanying plant assemblages revealed significant differences between cytotypes along the entire transect but
not within the lower part only, where both cytotypes co-occur. This suggests the presence of ecological differentiation between
cytotypes with the diploid possessing the broader ecological niche. No tetraploids were detected, indicating the presence
of strong crossing barriers.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
82.
Teresa Teruel Angela M. Valverde Manuel Benito Margarita Lorenzo 《Journal of cellular physiology》1996,166(3):577-584
The presence of transforming growth factor β1 (TGF-β1) for 24 or 48 h stimulated DNA synthesis, the percentage of cells in the S + G2/M phases of the cell cycle, and cell number, as compared to quiescent cells. The mitogenic capacity of TGF-β1 (1 pM) was similar to that shown by 10% fetal calf serum (FCS). TGF-β1 for 48 h increased by 5-fold the percentage of cells containing (3H)thymidine-labeled nuclei as compared to quiescent cells. In addition, single fetal brown adipocytes, showing their typical multilocular fat droplets phenotype, become positive for (3H)thymidine-labeled nuclei in response to TGF-β1. Moreover, TGF-β1 induced the mRNA expression of a complete set of proliferation-related genes, such as c-fos (30 min), c-myc and β-actin (2 h), and H-ras, cdc2 kinase, and glucose 6-phosphate dehydrogenase (G6PD) at 4 and 8 h, as compared to quiescent cells. Concurrently, TGF-β1 for 12 h increased the protein content of proliferating cellular nuclear antigen (PCNA) by 6-fold and p21-ras by 2-fold. Although our results demonstrate that TGF-β1 induces the expression of very early genes related to cell proliferation, TGF-β1 could be acting either as a mitogen or as a survival factor to induce proliferation in fetal brown adipocytes. © 1996 Wiley-Liss, Inc. 相似文献
83.
Abscisic acid and gibberellin-like substances in roots and root nodules ofGlycine max 总被引:1,自引:0,他引:1
Summary The content of endogenous gibberellin (GA)-like substances of roots and root nodules of SOya, and GA production byRhizobium japonicum cultures, were investigated by a combined thin layer chromatographic (TLC)-dwarf pea epicotyl bioassay technique. GAs were
more concentrated in root nodules than in the roots, totalling 1.34 and 0.16 nM GA3 equivalents g−1 dry wt. respectively. GA production byR. japonicum cultures was demonstrated (1.00 nM GA3 equivalentsl
−1) and comparison of the GA components of plant and bacterial culture medium extracts, suggested that rhizobial GA production
may contribute to the nodule GA content.
Cis-trans abscisic acid (ABA) was identified in root and nodule extracts by TLC-gas liquid chromatography (GLC), and amounted
to 0.18 and 2.21 nM g−1 dry wt. respectively, whereas 0.30 and 4.63 nM ABA equivalents g−1 dry wt. were detected by a TLC-wheat embryo bioassay technique. ABA was not detected in extracts of bacterial cultures. 相似文献
84.
Gravity independence of seed-to-seed cycling in Brassica rapa 总被引:2,自引:0,他引:2
Musgrave ME Kuang A Xiao Y Stout SC Bingham GE Briarty LG Levenskikh MA Sychev VN Podolski IG 《Planta》2000,210(3):400-406
Growth of higher plants in the microgravity environment of orbital platforms has been problematic. Plants typically developed
more slowly in space and often failed at the reproductive phase. Short-duration experiments on the Space Shuttle showed that
early stages in the reproductive process could occur normally in microgravity, so we sought a long-duration opportunity to
test gravity's role throughout the complete life cycle. During a 122-d opportunity on the Mir space station, full life cycles
were completed in microgravity with Brassica rapa L. in a series of three experiments in the Svet greenhouse. Plant material was preserved in space by chemical fixation, freezing,
and drying, and then compared to material preserved in the same way during a high-fidelity ground control. At sampling times
13 d after planting, plants on Mir were the same size and had the same number of flower buds as ground control plants. Following
hand-pollination of the flowers by the astronaut, siliques formed. In microgravity, siliques ripened basipetally and contained
smaller seeds with less than 20% of the cotyledon cells found in the seeds harvested from the ground control. Cytochemical
localization of storage reserves in the mature embryos showed that starch was retained in the spaceflight material, whereas
protein and lipid were the primary storage reserves in the ground control seeds. While these successful seed-to-seed cycles
show that gravity is not absolutely required for any step in the plant life cycle, seed quality in Brassica is compromised by development in microgravity.
Received: 3 August 1999 / Accepted: 27 August 1999 相似文献
85.
Irfan Jawed Margarita Velarde Roland Därr Katherine I. Wolf Karen Adams Aradhana M. Venkatesan Sanjeeve Balasubramaniam Marianne S. Poruchynsky James C. Reynolds Karel Pacak Tito Fojo 《Cellular and molecular neurobiology》2018,38(5):1099-1106
Patients harboring germline mutations in the succinate dehydrogenase complex subunit B (SDHB) gene present with pheochromocytomas and paragangliomas (PPGL) that are more likely malignant and clinically aggressive. The combination chemotherapy cyclophosphamide, vincristine, and dacarbazine (CVD) was retrospectively evaluated in patients with SDHB-associated metastatic PPGL.Query Twelve metastatic PPGL patients harboring SDHB mutations/polymorphisms with undetectable SDHB immunostaining were treated with CVD. CVD therapy consisted of 750 mg/m2 cyclophosphamide with 1.4 mg/m2 vincristine on day 1 and 600 mg/m2 dacarbazine on days 1 and 2, every 21–28 days. Treatment outcome was determined by RECIST criteria as well as determination of response duration and progression-free and overall survivals. A median of 20.5 cycles (range 4–41) was administered. All patients had tumor reduction (12–100% by RECIST). Complete response was seen in two patients, while partial response was observed in 8. The median number of cycles to response was 5.5. Median duration of response was 478 days, with progression-free and overall survivals of 930 and 1190 days, respectively. Serial [18F]-fluorodeoxyglucose positron emission tomography and computed tomography imaging demonstrated continued incremental reduction in maximal standardized uptake values (SUVmax) values in 26/30 lesions. During treatment administration, the median SUV decreased from?> 25 to?< 6, indicating the efficacy of chemotherapy over a prolonged period of time. Prolonged therapy results in continued incremental tumor reduction, and is consistent with persistent drug sensitivity. CVD chemotherapy is recommended to be considered part of the initial management in patients with metastatic SDHB-related PPGL. 相似文献
86.
Summary Capillaries, pericytes and microglial cells in layer I of the cerebral cortex of normal adult cats have been studied with electron microscopy. The data obtained in this study show that pericytes are cells which are able to transform themselves into microglial cells by virtue of an activation process in which the astrocytic neuroglia appears to play a decisive role. By virtue of its structure, its mesodermic origin and its function the microglia has to be distinguished clearly from the astrocytic neuroglia and the oligodendroglia.This study was partly supported by a grant from the Seguridad Social, Instituto Nacional de Previsión. 相似文献
87.
Nucleotide sequence of the metH gene of Escherichia coli K-12 and comparison with that of Salmonella typhimurium LT2 总被引:4,自引:0,他引:4
The Escherichia coli K-12 metH gene, encoding the vitamin B12-dependent homocysteine transmethylase, is located between iclR and lysC in the 91-min region of the chromosome. The metH gene has been sequenced and reveals an open reading frame of 3600 bp encoding a polypeptide of 1200 amino acids (aa) with a calculated Mr of 132 628. The first 414 aa of the deduced polypeptide sequence are 92% identical to the 414 aa deduced from the partially sequenced Salmonella typhimurium LT2 metH gene. In-frame fusions of metH to lacZ were used to confirm the reading frame of the metH gene and to study its regulation. metH was repressed tenfold, presumably indirectly, by L-methionine and the metJ gene product, while vitamin B12 did not induce de novo synthesis of MetH. 相似文献
88.
Cañadas O Guerrero R García-Cañero R Orellana G Menéndez M Casals C 《Biochemistry》2004,43(30):9926-9938
Tacrolimus (FK506) is a hydrophobic immunosuppressive agent that rapidly penetrates the plasmatic membrane and inhibits the signal transduction cascade of T lymphocytes. The objective of this study was the characterization of liposomal FK506 with surfactant-like phospholipids to be administered intratracheally after lung transplantation or in inflammatory lung diseases. We evaluated the optimal incorporation of FK506 in dipalmitoylphosphatidylcholine (DPPC) and DPPC/1-palmitoyl-2-oleoylphosphatidylglycerol (POPG) monolayers and bilayers and the effects of FK506 on the physical properties of DPPC and DPPC/POPG (8:2 w/w) vesicles. In addition, we assessed the immunosuppressive effects of surfactant-like phospholipid vesicles containing different amounts of FK506 on T-cell proliferation and interleukin 2 production. From surface pressure measurements of FK506/DPPC and FK506/DPPC/POPG mixed monolayers, we determined that FK506 was embedded into these monolayers up to an FK506 concentration of about 0.4 mol %. Beyond this concentration, FK506 was not quantitatively incorporated into the monolayer, suggesting possible concentration-dependent aggregation of tacrolimus. The incorporation of FK506 into DPPC monolayers, at concentrations 相似文献
89.
John S. Debenham Thomas H. Graham Andreas Verras Yong Zhang Matthew J. Clements Jeffrey T. Kuethe Christina Madsen-Duggan Wensheng Liu Urmi R. Bhatt Dunlu Chen Qing Chen Margarita Garcia-Calvo Wayne M. Geissler Huaibing He Xiaohua Li JeanMarie Lisnock Zhu Shen Xinchun Tong Dong-Ming Shen 《Bioorganic & medicinal chemistry letters》2013,23(23):6228-6233
The synthesis, SAR, binding affinities and pharmacokinetic profiles are described for a series of cyclohexane-based prolylcarboxypeptidase (PrCP) inhibitors discovered by high throughput screening. Compounds show high levels of ex vivo target engagement in mouse plasma 20 h post oral dose. 相似文献
90.
Response of zooplankton to nutrient enrichment and fish in shallow lakes: a pan-European mesocosm experiment 总被引:4,自引:1,他引:4
Kirsi Vakkilainen Timo Kairesalo Jaana Hietala David M. Balayla Eloy Bécares Wouter J. Van de Bund Ellen Van Donk Margarita Fernández-Aláez Mikael Gyllström Lars-Anders Hansson Maria R. Miracle Brian Moss Susana Romo Juan Rueda Deborah Stephen 《Freshwater Biology》2004,49(12):1619-1632
1. Responses of zooplankton to nutrient enrichment and fish predation were studied in 1998 and 1999 by carrying out parallel mesocosm experiments in six lakes across Europe. 2. Zooplankton community structure, biomass and responses to nutrient and fish manipulation showed geographical and year‐to‐year differences. Fish had a greater influence than nutrients in regulating zooplankton biomass and especially the relative abundances of different functional groups of zooplankton. When fish reduced the biomass of large crustaceans, there was a complementary increase in the biomasses of smaller crustacean species and rotifers. 3. High abundance of submerged macrophytes provided refuge for zooplankton against fish predation but this refuge effect differed notably in magnitude among sites. 4. Large crustacean grazers (Daphnia, Diaphanosoma, Sida and Simocephalus) were crucial in controlling algal biomass, while smaller crustacean grazers and rotifers were of minor importance. Large grazers were able to control phytoplankton biomass even under hypereutrophic conditions (up to 1600 μg TP L?1) when grazer biomass was high (>80–90 μg dry mass L?1) or accounted for >30% of the grazer community. 5. The littoral zooplankton community was less resistant to change following nutrient enrichment in southern Spain, at high temperatures (close to 30 °C), than at lower temperatures (17–23 °C) characterising the other sites. This lower resistance was because of a greater importance of nutrients than zooplankton in controlling algal biomass. 6. Apart from the reduced role of large crustacean grazers at the lowest latitude, no consistent geographical patterns were observed in the responses of zooplankton communities to nutrient and fish manipulation. 相似文献