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991.
David A. Flemer Roman S. Stanley Barbara F. Ruth Charles M. Bundrick Paul H. Moody James C. Moore 《Hydrobiologia》1995,308(2):85-101
Two six-week laboratory experiments were conducted to evaluate effects of pesticides and microcosm size on benthic estuarine
macroinvertebrate recolonization. Sediments fortified with the pesticides (fenvalerate: controls, 5 (low) and 50 μg g−1 wet sediment (high); endosulfan: controls, 1 (low) and 10 μg g−1 wet sediment (high)) were fine-grained, organically rich (approximately 3.5% organic carbon and 22% dry weight) material.
Relative dominance of the four most abundant taxa in both experiments was consistent among treatments with few exceptions.
The amphipod,Corophium acherusicum, dominated abundance in both experiments.
In the fenvalerate experiment, large trays (400 cm2) contained significantly (p<0.05) more total number of taxa (TNT) than small microcosms (144 cm2) but tray size was not significantly related to total number of organisms (TNO). When size was adjusted to a common unit
area, small trays contained significantly more TNO than large containers. Adjusted abundance of small trays was 2.5 times
that of large containers; a ratio close to that of microcosm sizes (i.e., 2.8). This result suggests that larval supply may have been inadequate to ‘aturate’ the available sediment in large containers.
Fenvalerate significantly reduced abundance in the high treatment compared to both controls and low treatment but low treatment
was not significantly different from controls. The amphipod,Corophium acherusicum, accounted for most of the decrease in abundance in response to fenvalerate. The holothruroid,Leptosynpta sp. and the polychaete,Mediomastus ambiseta, increased in abundance significantly with increased concentration of fenvalerate.
Combined effects of actual microcosm size and concentration of endosulfan were not significant for TNO or TNT. As in the fenvalerate
experiment, adjusted abundance of small microcosms was 2.6 times that of large trays which approximated the ratio of unit
area between microcosm sizes. Abundance of a few taxa responded significantly to adjusted and unadjusted unit area. Abundance
of the tunicate,Molgula manhattensis, increased significantly with increased concentration of endosulfan. Abundance was affected by sample location (e.g., interiorvs exterior cores) within microcosms. Abundance adjusted to unit area resulted in significantly greater TNO in externalvs internal cores. This has importance for sequential sub-sampling of microcosms to determine temporal dynamics.
Statistically significant effects were measured in benthic community structure associated with microcosm size; however, the
magnitude was relatively small. There appears to be no major biological reason to select one microcosm size over the other
for screening for contaminant effects. Where feasible, the small trays provide savings in sample preparation and analysis,
allow more replicates where laboratory space is limiting and generate less chemical waste. These benefits may be off-set by
less ‘artifacts’ associated with edge effects of larger microcosms and the need for a larger mass of sediment to accommodate
additional analytical requirements (e.g., thin vertical surficial samples to refine contaminant exposure at the sediment/water
interface). 相似文献
992.
Swim Stress Increases the Potency of Glycine at the N-Methyl-d-Aspartate Receptor Complex 总被引:1,自引:0,他引:1
Gabriel Nowak †Anna Redmond †Mairead McNamara ‡ Ian A. Paul 《Journal of neurochemistry》1995,64(2):925-927
Abstract: We have previously demonstrated that chronic administration of antidepressants results in a reduction in the potency of glycine to displace 5,7-[3 H]dichlorokynurenic acid (5,7-[3 H]-DCKA) from the strychnine-insensitive glycine recognition site of the NMDA receptor complex. We now report that exposure of rats to the forced swim test results in a 56% increase in the potency of glycine to displace 5,7-[3 H]DCKA from frontal cortical homogenates. These data are consistent with the hypothesis that the forced swim test, a preclinical screen sensitive to acute administration of antidepressant drugs and NMDA receptor antagonists, also results in adaptation of the NMDA receptor complex. Moreover, these data lend further support to the hypothesis that glutamatergic pathways are involved in the neurobiological response to stress and, potentially, in the pathophysiology of depression. 相似文献
993.
Shiori Tamamizu A. Paul Todd Mark G. McNamee 《Cellular and molecular neurobiology》1995,15(4):427-438
Summary 1. Site directed mutagenesis was used to alter the structure ofTorpedo californica nicotinic acetylcholine receptor (nAChR) and to identify amino acid residues which contribute to noncompetitive inhibition by quinacrine. Mutant receptors were expressed inXenopus laevis oocytes injected within vitro synthesized mRNA and the whole cell currents induced by acetylcholine (ACh) were recorded by two electrode voltage clamp.2. A series of mutations of a highly conserved Arg at position 209 of the subunit ofTorpedo californica nAChR revealed that positively charged amino acids are required for functional receptor expression. Mutation of Arg to Lys (R209K) or His (R209H) at position 209 shifted the EC50 for ACh slightly from 5µM to 12µM and increased the normalized maximal channel activity 8.5-and 3.2-fold, respectively.3. These mutations altered the sensitivity of nAChR to noncompetitive inhibition by quinacrine. The extent of inhibition of ion channel function by quinacrine was decreased as pH increased in both wild type and mutant nAChR suggesting that the doubly charged form of quinacrine was responsible for the inhibition.4. Further mutations at different positions of the subunit suggest the contribution of Pro and Tyr residues at positions 211 and 213 to quinacrine inhibition whereas mutationsI210A andL212A did not have any effects. None of these mutations changed the sensitivity of nAChR to inhibition by a different noncompetitive inhibitor, chlorpromazine.5. These findings support a hypothesis that the quinacrine binding site is located in the lumen of the ion channel. In addition, the quantitative effect of point mutations at alternate positions on the sensitivity of quinacrine inhibition suggests that the secondary structure at the beginning of M1 region might be sheet structure. 相似文献
994.
Measurement of cytokine antibodies. Test development 总被引:1,自引:0,他引:1
Several assays have been used for detection of antibodies against cytokines. The choice of assay is greatly dependent on the
intended goal, e.g. detection of naturally occurring antibodies or therapy induced antibodies. The different assays can be
grouped in 2 categories. The interference or indirect assays are based on the detection of the test sample interference with
the biological activity, with detection of the cytokine in EIA or with binding to cellular receptors. In direct assays cytokine
antibodies are detected by binding to solid phase fixed cytokines, followed by incubation with a secondary enzyme-labelled
anti-human Ig antibody or by binding to125I-labelled cytokines in RIA. 相似文献
995.
Paul G. Braunschweiger Vathsala S. Basrur Dayna Cameron Laura Sharpe Octavio Santos James P. Perras Bernd-Uwe Sevin Arnold M. Markoe 《Biotherapy》1997,10(2):129-137
The modulation of cisPlatin cytotoxicity by interleukin-1 (IL-1α) was studied in cultures of SCC-7 tumor cells with and without
tumor macrophages to examine potential mechanisms for the synergistic antitumor activity of cisPlatin and IL-1α in SCC-7 solid
tumors. Neither IL-1α nor tumor macrophages affected the survival of clonogenic tumor cells and IL-1α had no direct effect
on tumor cell growthin vitro. Macrophages had no direct effect on cisPlatin sensitivity (IC90=6.0 μM), but, the addition of IL-1α (500–2000U/ml) to co-cultures of cisPlatin pretreated tumor cells and resident tumor
macrophages increased cell killing (IC90=3.1 μM). Similar responses were seen in primary cultures treated with cisPlatin before IL-1α. The modulation of cisPlatin
cytotoxicity by IL-1α exhibited a biphasic dose response that paralleled the IL-1α dose dependent release of H2O2by resident tumor macrophages. Further, IL-1α modification of cisPlatin cytotoxicity was prompt and inhibited by catalase.
CisPlatin and exogenous H2O2 (50 μM) produced more than additive SCC-7 clonogenic cell kill and hydroxyl radicals played an important role in the response.
Interleukin-1 modulation of cisPlatin cytotoxicity was schedule dependent. IL-1α treatment for 24 hrs, before cisPlatin, produced
drug resistance (IC90=11.1 μM). Our study shows that IL-1α can stimulate tumor macrophages to release pro-oxidants that modify cellular chemosensitivity
in a schedule and dose dependent fashion. Our findings may also provide a mechanistic explanation for the synergistic antitumor
activity of cisPlatin and IL-1αin vivo. 相似文献
996.
The zebrafish is a polular nonmammalian model for studies of neural development. We have derived cell cultures, initiated from blastula-stage zebrafish embryos, that differentiate in vitro into neurons and astrocytes. Cultures were initiated in basal nutrient medium supplemented with bovine insulin, trout serum, trout embryo extract and fetal bovine serum. After two weeks in culture the cells exhibited extensive neurite outgrowth and possessed elevated levels of acetylcholinesterase enzyme activity. Ultrastructural analysis revealed that the neurites possessed microtubules, synaptic vessicles and areas exhibiting growth cone morphology. The cultures expressed proteins recognized by antibodies to the neuronal and astrocyte-specific markers, neurofilament and glial fibrillary acidic protein (GFAP). Poly-D-lysine substrate stimulated neurite outgrowth in the cultures and inhibited the growth of nonneuronal cells. Medium conditioned by the buffalo rat liver line, BRL, promoted the growth and survival of the cells in culture. Mitotically active cells were identified in cultures that had undergone extensive differentiation. The embryo cell cultures provide an in vitro system for investigations of biochemical parameters influencing zebrafish neuronal cell growth and differentiation. 相似文献
997.
Positive role of macaque cytotoxic T lymphocytes during SIV infection: decrease of cellular viremia and increase of asymptomatic clinical period 总被引:1,自引:0,他引:1
998.
Xiangning Deng Jennifer Moran Neal G. Copeland Debra J. Gilbert Nancy A. Jenkins Paul Primakoff Patricia A. Martin-DeLeon 《Mammalian genome》1997,8(2):94-97
We have determined the chromosomal localization of the murine gene encoding the 68-kDa sperm adhesion molecule 1, Spam1 or Ph-20. Using two independent approaches, fluorescence in situ hybridization (FISH) and interspecific backcross analysis, we show
that Spam1 maps to proximal mouse Chromosome (Chr) 6. This map position is within the conserved linkage group corresponding to human
Chr 7q, where the human homolog, SPAM 1, has been shown to map previously. Genetic mapping shows the gene to be very closely
linked to Met, one of the most proximal loci on MMU 6. It thus places the gene near the centromere and the junction of the Rb(6.16)24Lub
and Rb(6.15)1Ald translocations. The essential role of the Spam1 sperm antigen in mouse sperm-egg interactions and its gene
location provide strong support for its candidacy as the gene involved in the dysfunction of mouse sperm bearing the Rb(6.16)24Lub
or Rb(6.15)1Ald translocation.
Received: 16 July 1996 / Accepted: 23 September 1996 相似文献
999.
Expression of insulin-like growth factor II (IGF-II) and histological changes in the thymus and spleen of transgenic mice overexpressing IGF-II 总被引:2,自引:0,他引:2
Leo T. M. Van der Ven Paul J. M. Roholl Maria G. Reijnen-Gresnigt Ruud J. Bloemen Sylvia C. van Buul-Offers 《Histochemistry and cell biology》1997,107(3):193-203
Previously, transgenic mice were constructed overexpressing human insulin-like growth factor II (IGF-II) under control of
the H2kb promoter. The IGF-II transgene was highly expressed in thymus and spleen, and these organs showed an increase in weight. In
the current study we have analyzed the sites of IGF-II mRNA expression, the distribution of IGF-II, IGF-I, and both IGF receptors,
and histomorphometrical changes in thymus and spleen. With in situ mRNA hybridization, expression of the IGF-II transgene
is found with high intensity in the thymic medulla and in the white pulp/marginal zone of the spleen, whereas there were scattered
positive cells in the thymic cortex and in the splenic red pulp. Hybridization was restricted to non-lymphocytic cells. Immunohistochemistry
revealed intense IGF-II peptide staining with the same distribution as IGF-II mRNA. There was additional intense IGF-II staining
of all elements in the splenic red pulp (including trabeculae) and diffuse, low level staining in the thymic cortex. These
findings were not observed in control mice. In the thymic medulla, most IGF-II producing cells co-labelled with keratin, whereas
a minor population also stained for the monocyte/macrophage marker MOMA-2. In the spleen, co-labelling of IGF-II producing
cells was found with MOMA-1 (marginal zone), or with the dendritic cell marker NLDC-145 (red pulp). IGF-I and both IGF receptors
were found in these organs in nearly all cell types, with a similar pattern in transgenic mice and in control animals. Histomorphometric
analysis revealed a marked increase of thymus cortex size and an increased trabecular size in the spleen. This suggests that
IGF-II overproduction induces local effects (auto/paracrine) in the thymic cortex, but not in the thymic medulla. Trabecular
growth in the spleen most likely is a distant effect (paracrine or endocrine) of IGF-II overproduction.
Accepted: 5 September 1996 相似文献
1000.