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71.
We have isolated a series of monoclonal antibodies that react to antigens in flowers of Nicotiana tabacum L. (tobacco) displaying specificity or preferentiality in their cell and tissue distributions. We immunized mice with extracts from tobacco flowers and then screened the hybridomas by enzyme-linked immunosorbent assay (ELISA) against extracts from leaves, sepals, petals, stamens and pistils; twenty five were chosen from the total screened. The antigens detected by about half of the antibodies were periodate-sensitive, implying that the epitopes were carbohydrate. Competition ELISA assays were used to determine if any antibodies were reacting to the same epitopes. Western blot analysis showed that while some antibodies reacted to specific bands, the bulk either failed to react or reacted to multiple bands, consistent with a glyco-conjugate nature for many of the antigens. Analysis of the spatial pattern of antigen distribution within tobacco flowers by immunolocalization showed that some antibodies recognized epitopes that were limited to very specific cells and tissues. We used the immunolocalization technique to analyze a mutant with stigmoid anthers: an antibody recognizing a pistil transmitting-tract antigen also reacted to cells in stigmoid anthers. Our results with this antibody set imply that biochemical differentiation within the tobacco flower includes cell-and tissue-specific glyco-moeities, and also that similarities, at the biochemical level, exist between a normal floral organ and the abnormal organ in a phenotype with a developmental switch.Abbreviations ELISA
enzyme-linked immunosorbent assay
- Fg
immunoglobulin
- kDa
kilodalton 相似文献
72.
Summary Water and sodium turnovers of 6–7 week old gentoo penguin chicks and breeding adults were measured using isotopically labelled water and sodium. Influx rates for chicks averaged 188 ml·kg-1·day-1 and 13.9 mmol·kg-1·day-1 for water and sodium, respectively. Chicks consumed an estimated 228 g·kg-1·day-1 fresh food or 886 kJ kg-1 day. These values correspond to 761 g·day-1 or 2945 kJ·day-1 for a gentoo chick mid-way through the growth period. Flux rates for adults attending chicks ranged from 199 to 428 ml·kg-1·day-1 for water and from 15 to 36 mmol·kg-1·ay-1 for sodium. 相似文献
73.
74.
Cyprian Weaver Robert L. Sorenson Brian Kobienia 《In vitro cellular & developmental biology. Plant》1988,24(2):108-116
Summary The purpose of this study was to develop a nonenzymatic method of isolating adult islets using atrophied pancreata from copper-deficient
rats and to analyze their morphologic characteristics and behavior in culture. This unusual model of isolation was studied
because islets remain intact in the course of dietary copper deficiency while the acinar glandular component of the pancreas
undergoes selective atrophy and lipomatosis. Small fragments containing islets were readily microdissected from atrophied
glands and placed in culture. Within 24 h the fragments congealed into small irregular- to spherical-shaped masses within
which the darker profile of islets could be distinguished. Within a period of 3 to 5 d, islet tissue began to bud from the
lipocytic mass until by Day 7 spherical aggregates of intact islet tissue separated from the residual fragments. Subsequent
to further in vitro treatment, these islets could be maintained as free viable spherical masses if periodically agitated,
as attached stationary islets which developed monolayer growth if left undisturbed and as aggregated masses of islet tissue
forming megaislets if combined in small groups. Grouped islets treated with actinomycin D and cycloheximide did not exhibit
aggregation when incubated with these inhibitors. This suggests that megaislet formation was an active process requiring protein-RNA
synthesis rather than passive clumping or aggregation that can accompany metabolically altered or dying islets undergoing
cellular shedding and adhesion. Immunohistochemical localization demonstrated that insulin, glucagon, somatostatin, and pancreatic
polypeptide-immunoreactive cell types were present within the islets derived from this technique. The cellular topography
of these islets was not unlike that described by others for islets cultured from enzymatic isolation. This culture model may
serve as a resource for mature, viable islets isolated without mechanical or enzymatic disaggregation which can have attenuating
effects on islet function.
This work was supported by a research grant from the Diabetes Research and Education Foundation. 相似文献
75.
Brian R. Monsma Alan G. Glaros Mark A. Lumley 《Applied psychophysiology and biofeedback》1988,13(2):113-122
The use of noncontingent feedback controls in studies of the efficacy and process of electromyographic (EMG) biofeedback may yield results confounded by differential expectancies for relaxation. Furthermore, the role of expectancies in producing psychological and physical relaxation as well as reducing muscle activity is unclear. This study investigated the effects of feedback delays and induced relaxation expectancies on EMG activity and experienced relaxation. One hundred four non-clinical subjects participated in one auditory frontal EMG biofeedback training session. Subjects were assigned to one of four computerized feedback delay conditions (0.0037, 0.7493, 2.2481, 6.7444 s) and to one of two relaxation expectancy conditions (positive or negative). During 20 minutes of biofeedback training, all groups decreased frontal activity. Feedback delays interacted with training epochs in affecting EMG; the longest delay group reduced frontal activity more slowly than the shortest delay group during training. Positive relaxation expectancies produced greater experienced relaxation than did negative relaxation expectancies. Instrumental and expectancy factors in EMG biofeedback appear to operate independently of each other by reducing physiological activity and producing psychological relaxation respectively.This study was completed by the first author under the direction of the second author in partial fulfillment of the requirements for the Master of Arts degree. We gratefully acknowledge the computerization advice and assistance provided by Larry Wheeler, and the assistance in data collection provided by Dawn Dexter and Michael Winstanley. 相似文献
76.
77.
Heng Xu John S. Partilla Brian R. de Costa Kenner C. Rice Richard B. Rothman 《Peptides》1992,13(6):1207-1213
Recent pharmacological data strongly support the hypothesis of δ receptor subtypes as mediators of both supraspinal and spinal antinociception (δ1 and δ2 receptors). In vitro ligand binding data, which are fully supportive of the in vivo data, are still lacking. A previous study indicated that [3H][
-Ala2,
-Leu5]enkephalin labels two binding sites in membranes depleted of μ binding sites by pretreatment with the site-directed acylating agent, 2-(p-ethoxybenzyl)-1-diethylaminoethyl-5-isothiocyanatobenzimidazole-HCI (BIT). The main goal of the present study was to develop a ligand-selectivity profile of the two δncx binding sites. The data indicated that naltrindole and oxymorphindole were relatively selective for site 1 (20-fold). [
-Ser2,Thr6]Enkephalin and deltorphin-II were only 2.7-fold and 2.2-fold selective for site 1. [
-Pen2,
-Pen5]Enkephalin and deltorphin-I were 80-fold and 38-fold selective for site 2.3-Iodo-Tyr-
-Ala-Gly-Phe-
-Leu was 52-fold selective for site 1. Morphine had moderate affinity for site 1 (Ki = 16 nM), and was about 11-fold selective for site 1. Thus, of the 10 drugs studied, only DPDPE and DELT-I were selective for site 2. Viewed collectively with other data, it is likely that the δ1 receptor and the δncx binding site are synonymous. 相似文献
78.
Brian Rodrigues Michael R. Spooner David L. Severson 《Molecular and cellular biochemistry》1992,116(1-2):33-37
An exogenous [3H]triolein emulsion was hydrolyzed by intact cardiac myocytes with functional LPL located on the cell surface. This surface-bound LPL could be released into the medium when cardiac myocytes were incubated with heparin. Incubation of cardiac myocytes with VLDL, or the products of TG breakdown, oleic acid or 2-monoolein, did not increase LPL activity in the medium. However, incubation of cardiac myocytes with either VLDL or oleic acid for > 60 min did reduce heparin-releasable LPL activity. In the heart, this inhibitory effect of FFA could regulate the translocation of LPL from its site of synthesis in the cardiac myocyte to its functional site at the capillary endothelium.Abbreviations LPL
lipoprotein lipase
- TG
triacylglycerol
- FFA
free fatty acids
- VLDL
very-low density lipoprotein 相似文献
79.
Sallie W. Chisholm Sheila L. Frankel Ralf Goericke Robert J. Olson Brian Palenik John B. Waterbury Lisa West-Johnsrud Erik R. Zettler 《Archives of microbiology》1992,157(3):297-300
Several years ago, prochlorophyte picoplankton were discovered in the N. Atlantic. They have since been found to be abundant within the euphotic zone of the world's tropical and temperate oceans. The cells are extremely small, lack phycobiliproteins, and contain divinyl chlorophyll a and b as their primary photosynthetic pigments. Phylogenies constructed from DNA sequence data indicate that these cells are more closely related to a cluster of marine cyanobacteria than to their prochlorophyte relatives Prochlorothrix and Prochloron. Several strains of this organism have recently been brought into culture, and herewith are given the name Prochlorococcus marinus. 相似文献
80.
We have constructed a plasmid which contains 22 copies of a 147 bp DNA fragment which contains the major DNA gyrase cleavage site from plasmid pBR322 (located at base-pair 990). We have found that this fragment is efficiently bound and cleaved by gyrase. The selectivity for the sequence corresponding to position 990 in pBR322 is maintained even when this site is located only 15 bp from one end of the 147 bp fragment. A strategy for the specific incorporation of a single thiophosphoryl linkage into the 147 bp fragment has been developed, and gyrase has been shown to catalyse efficient cleavage of fragments bearing phosphorothioate linkages at the gyrase cleavage site in one or both strands. 相似文献