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231.
Declerck P Behets J Lammertyn E Lebeau I Anné J Ollevier F 《Canadian journal of microbiology》2006,52(6):584-590
The presence of high levels of Legionella pneumophila in man-made aquatic systems correlates with the incidence of nosocomial Legionnaires' disease. This requires a rapid, reliable, and sensitive quantification of L. pneumophila concentrations in suspected water systems. In this research, a homologous competitor was developed and evaluated in a L. pneumophila competitive polymerase chain reaction (cPCR) to quantify this human pathogen in a quick, cost-effective, and reliable way. Accuracy of cPCR was evaluated by analyzing cooling tower and tap water samples spiked with known concentrations of L. pneumophila bacteria, in parallel with the standard culture method. Legionella pneumophila amounts detected and calculated from cPCR and culture correlated very well: r = 0.998, P = 0.002 for tap water and r = 0.990, P = 0.009 for cooling tower water. Nevertheless, for both kinds of water samples, mean numbers of L. pneumophila calculated from cPCR results were always higher than those obtained by culture. This study makes it clear that the rapid, sensitive, and cost-effective L. pneumophila cPCR is a promising alternative to the standard time-consuming culture method and expensive real-time PCR to enumerate L. pneumophila bacteria in environmental water samples. 相似文献
232.
233.
Non-indigenous arthropods are increasingly being introduced into new areas worldwide and occasionally they cause considerable
ecological and economic harm. Many invasive arthropods particularly pose problems to areas of human habitation and native
ecosystems. In these cases, the use of environmentally benign materials, such as host-specific entomopathogens, can be more
desirable than broader spectrum control tactics that tend to cause greater non-target effects. The majority of successful
eradication programs using arthropod pathogens have targeted invasive Lepidoptera with Bacillus thuringiensis kurstaki (Btk), such as eradication efforts against the gypsy moth, Lymantria dispar (L.), in North America and New Zealand. Both Btk and Lymantria dispar nucleopolyhedrovirus have been successfully used in efforts to limit the spread of L. dispar in the United States. For invasive arthropod species that are well established, suppression programs have successfully used
arthropod-pathogenic viruses, bacteria, fungi and nematodes for either short- or long-term management. We will summarize the
use of pathogens and nematodes in invasive arthropod management programs within a general context, and compare the use of
microbes in gypsy moth management with diverse microbes being developed for use against other invasive arthropods. 相似文献
234.
235.
For this report, we examined the toxic effects of three plant-derived isothiocyanate compounds on second-stage juveniles (J2) of Heterodera glycines. We found significant differences among compounds in the concentration required to affect nematodes, according to mortality and behavioral measurements. The concentrations required to affect behavior were significantly lower than those required for mortality. Both mortality and behavioral measurements were used to investigate whether nematodes in a quiescent state display decreased sensitivity to isothiocyanates compared with actively moving nematodes. Mortality measurements revealed that quiescent nematodes were significantly less sensitive to isothiocyanates than active nematodes. All behavioral measurements following exposure to benzyl- and phenyl isothiocyanate showed significant differences in sensitivity between quiescent and active nematodes. However, significant differences between quiescent and active nematodes were observed in only one of the five behavioral measurements following exposure to allyl isothiocyanate. These results expand the list of plant-derived compounds toxic to H. glycines and illustrate the impact of behavioral quiescence on nematode sensitivity to exogenous toxins. 相似文献
236.
Ann H. Klopp Lara Lacerda Anshul Gupta Bisrat G. Debeb Travis Solley Li Li Erika Spaeth Wei Xu Xiaomei Zhang Michael T. Lewis James M. Reuben Savitri Krishnamurthy Mauro Ferrari Rogério Gaspar Thomas A. Buchholz Massimo Cristofanilli Frank Marini Michael Andreeff Wendy A. Woodward 《PloS one》2010,5(8)
Introduction
Normal and malignant breast tissue contains a rare population of multi-potent cells with the capacity to self-renew, referred to as stem cells, or tumor initiating cells (TIC). These cells can be enriched by growth as “mammospheres” in three-dimensional cultures.Objective
We tested the hypothesis that human bone-marrow derived mesenchymal stem cells (MSC), which are known to support tumor growth and metastasis, increase mammosphere formation.Results
We found that MSC increased human mammary epithelial cell (HMEC) mammosphere formation in a dose-dependent manner. A similar increase in sphere formation was seen in human inflammatory (SUM149) and non-inflammatory breast cancer cell lines (MCF-7) but not in primary inflammatory breast cancer cells (MDA-IBC-3). We determined that increased mammosphere formation can be mediated by secreted factors as MSC conditioned media from MSC spheroids significantly increased HMEC, MCF-7 and SUM149 mammosphere formation by 6.4 to 21-fold. Mammospheres grown in MSC conditioned media had lower levels of the cell adhesion protein, E-cadherin, and increased expression of N-cadherin in SUM149 and HMEC cells, characteristic of a pro-invasive mesenchymal phenotype. Co-injection with MSC in vivo resulted in a reduced latency time to develop detectable MCF-7 and MDA-IBC-3 tumors and increased the growth of MDA-IBC-3 tumors. Furthermore, E-cadherin expression was decreased in MDA-IBC-3 xenografts with co-injection of MSC.Conclusions
MSC increase the efficiency of primary mammosphere formation in normal and malignant breast cells and decrease E-cadherin expression, a biologic event associated with breast cancer progression and resistance to therapy. 相似文献237.
Pawel Nowak Derek C. Cole Ann Aulabaugh Jonathan Bard Rajiv Chopra Rebecca Cowling Kristi Y. Fan Baihua Hu Steve Jacobsen Minakshi Jani Guixan Jin Mei-Chu Lo Michael S. Malamas Eric S. Manas Rani Narasimhan Peter Reinhart Albert J. Robichaud Joseph R. Stock Joan Subrath Kristine Svenson John W. Ellingboe 《Bioorganic & medicinal chemistry letters》2010,20(2):632-635
8,8-Diphenyl-2,3,4,8-tetrahydroimidazo[1,5-a]pyrimidin-6-amine (1) was identified through HTS, as a weak (micromolar) inhibitor of BACE1. X-Ray crystallographic studies indicate the 2-aminoimidazole ring forms key H-bonding interactions with Asp32 and Asp228 in the catalytic site of BACE1. Lead optimization using structure-based focused libraries led to the identification of low nanomolar BACE1 inhibitors such as 20b with substituents which extend from the S1 to the S3 pocket. 相似文献
238.
Homocitrate synthase (HCS) catalyzes one of the regulated steps of the alpha-aminoadipate pathway for lysine biosynthesis in fungi. The kinetic mechanism of regulation of HCS from Saccharomyces cerevisiae by Na+ and the feedback inhibitor lysine was studied by measuring the initial rate in the absence and presence of the effectors. The data suggest that Na+ is an activator at low concentrations and an inhibitor at high concentrations and that these effects occur as a result of the monovalent ion binding to two different sites in the free enzyme. Inhibition and activation by Na+ can occur simultaneously, with the net rate of the enzyme determined by Na+/K(iNa+) and Na+/K(act), where K(iNa+) and K(act) are the inhibition and activation constants, respectively. The inhibition by Na+ was eliminated at high concentrations of acetyl-CoA, the second substrate bound, but the activation remained. Fluorescence binding studies indicated that lysine bound with high affinity to its binding site as an inhibitor. The inhibition by lysine was competitive versus alpha-ketoglutarate and linear in the physiological range of lysine concentrations up to 5 mm. The effects of Na+ and lysine were independent of one another. A model is developed for regulation of HCS that takes into account all of the effects discussed above. 相似文献
239.
Cardiovascular disease, of which atherosclerosis is an important component, is the leading cause of death in the western world. Although there are well-defined risk factors for atherosclerosis, these factors do not account for all incidences of the disease. Because atherosclerotic processes are typified by chronic inflammatory responses, which are similar to those that are elicited by chronic infection, the role of infection in promoting or accelerating atherosclerosis has received renewed attention. This review focuses on the accumulating evidence that chronic infection with Chlamydia pneumoniae, a ubiquitous human respiratory pathogen, might contribute to atherosclerotic lesion progression. 相似文献
240.
Marc van Bilsen Anneleen Daniels Olaf Brouwers Ben J. A. Janssen Wouter J. A. Derks Agnieszka E. Brouns Chantal Munts Casper G. Schalkwijk Ger J. van der Vusse Frans A. van Nieuwenhoven 《PloS one》2014,9(1)