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91.
M H Stone R Wilkinson I G Stother 《The Journal of bone and joint surgery. British volume》1989,71(2):217-221
A manufacturing technique to increase the bonding between bone cement and metal prostheses has been assessed in the laboratory by "push-out" tests, and the effects of contamination of the cement and of the prosthesis with blood and intramedullary contents have been studied. The technique, known as pre-coating, increases bond strength; this increase is preserved after contamination of the cement which does, however, cause some lowering of interface shear strength. The implications for clinical practice are discussed. 相似文献
92.
Comparison of bovine serum and colostral antibody: effect of colostral antibody on vaccination of calves for contagious bovine pleuroneumonia 下载免费PDF全文
S. S. Stone 《Immunology》1970,18(3):369-377
Calves born of cows that have been recently vaccinated with the T-1 strain of Mycoplasma mycoides var mycoides do not have antibodies in their sera prior to receiving colostrum from their dams.
The concentration of antibody in colostrum may be higher than that in serum but, on examination by gel filtration, reductive splitting with 2-mercapto-ethanol, and sucrose density centrifugation, it is qualitatively similar to that of the sera. Colostral antibody is absorbed unchanged through the gut wall and can suppress a response to T-1 vaccine, measured by the complement fixation test (CFT), for at least 60 days. Normal calves, 1–7 days old, can respond to a T-1 vaccine in a manner similar to that of adult cattle.
相似文献93.
94.
Prime SS Eveson JW Stone AM Huntley SP Davies M Paterson IC Robinson CM 《The Journal of pathology》2004,203(4):927-932
This study examined the behaviour of nine human malignant oral keratinocyte cell lines following orthotopic transplantation to the floor of the mouth of athymic mice. Tumourigenesis, local spread, and metastatic dissemination were correlated with known cellular responses to transforming growth factor-beta 1 (TGF-beta 1). Six of nine cell lines were tumourigenic; four of these cell lines showed local spread which was characterized by vascular and bone invasion. Metastatic spread was uncommon, with only 9% of animals with primary tumours developing metastases and these were almost exclusively found in the regional lymph nodes; there was one pulmonary metastasis and no liver deposits. Tumour cell behaviour did not reflect the clinical stage of the original tumours. Cell lines that were resistant to TGF-beta 1-induced growth inhibition were more likely to form primary tumours, exhibit local spread, and metastasize than cells that were growth-inhibited by the ligand. The data demonstrate that tumourigenicity and tumour behaviour in this orthotopic mouse model varied between cell lines and that the pattern of local invasion and metastasis was similar to that seen in human oral cancer. Furthermore, cell lines that were refractory to the growth inhibitory effects of TGF-beta 1 behaved more aggressively than cells that underwent ligand-induced cell-cycle arrest. 相似文献
95.
The authors prospectively studied consecutive neurological inpatients with either motor conversion symptoms or pseudoseizures of recent onset. Patients were administered a structured psychiatric diagnostic interview, a measure of perceived parental care, and a life events inventory. They found that patients with pseudoseizures (N=20, mean age=27 years): 1) were younger than patients with motor conversion symptoms (N=30, mean age=39 years), 2) were more likely to have a borderline personality disorder), 3) were more likely to have a lower perception of parental care and to report incest, and 4) reported more life events in the 12 months before symptom onset. These differences in their characteristics and associated factors raised the question of whether it is helpful to group patients with pseudoseizures and motor conversion symptoms in a single diagnostic category of conversion disorder. An alternative view, that gives primacy to the symptoms rather than a disorder, may enable more precise research questions to be posed. 相似文献
96.
Quantitative analysis of wear and wear debris from metal-on-metal hip prostheses tested in a physiological hip joint simulator 总被引:3,自引:0,他引:3
Firkins PJ Tipper JL Saadatzadeh MR Ingham E Stone MH Farrar R Fisher J 《Bio-medical materials and engineering》2001,11(2):143-157
Osteolysis and loosening of artificial joints caused by UHMWPE wear debris has prompted renewed interest in metal-on-metal (MOM) hip prostheses. This study investigated the wear and wear debris morphology generated by MOM prostheses in a physiological anatomical hip simulator for different carbon content cobalt chrome alloys. The low carbon pairings demonstrated significantly higher "bedding in" and steady state wear rates than the mixed and high carbon pairings. The in vitro wear rates reported here were up to one or two orders of magnitude lower than the clinical wear rates for first-generation MOM hip prostheses. Two methods for characterising the metal wear debris were developed, involving digestion, scanning electron microscopy and transmission electron microscopy. The metal wear particles characterised by the two methods were similar in size, 25-36 nm, and comparable to particles isolated from periprosthetic tissues from first and second-generation MOM hip prostheses. Due to the small size of the metal particles, the number of particles generated per year for MOM prostheses in vitro was estimated to be up to 100 times higher than the number of polyethylene particles generated per year in vivo. The volumetric wear rates were affected by the carbon content of the cobalt chrome alloy and the material combinations used. However, particle size and morphology was not affected by method of particle characterisation, the carbon content of the alloy or material combination. 相似文献
97.
The response of primary human peripheral blood mononuclear phagocytes to challenge with polyethylene particles of known size and dose was evaluated. Particles with mean sizes of 0.21, 0.49, 4.3, 7.2, and 88 microm were co-cultured with cells for 24 h prior to the assessment of cell viability and production of the osteolytic mediators IL-1beta, IL-6, TNFalpha, GM-CSF and PGE2. All particle fractions were evaluated at particle volume (microm3) to cell number ratios of 10:1 and 100:1 which were previously identified as being the most biologically active and clinically relevant. The heterogeneity of human individuals was clearly evident both in the profile and the magnitude of the response of the donors evaluated in this study (the response of donor 5 being 2- to 15-fold lower than that of the other donors). Only the sub-micrometre particles stimulated significantly enhanced cytokine secretion at the ratios tested: mean particle sizes of 0.49 and 0.21 microm being the most biologically active. Macrophages stimulated with particles outside this size range produced considerably lower levels of mediator. These results compared favourably with the results of earlier studies, which demonstrated that particles within the phagocytosable size range (0.1-10 microm) were the most biologically active. These results, therefore, confirm earlier findings and suggest that the size and volume of polyethylene particles are critical factors in macrophage activation. Furthermore, they suggest that the heterogeneity of human individuals may be another important factor in determining implant life and could provide the basis for a valuable diagnostic tool to identify those patients most at risk of implant loosening. 相似文献
98.
1. 2,4-dinitrophenol, 2,4-dinitrophenetole, 2,4-dinitronaphthol, 4,6-dinitro-o-cresol, and to a lesser extent picric acid, produced an increase in bile flow and a rise in body temperature in the anaesthetized dog. The total biliary bromsulphalein (BSP) excretion in unit time was either slightly reduced, increased or remained at its pre-injection level.2. Picramic acid, the nitrochlorophenols and 2,4-dinitrobenzaldehyde caused a moderate increase in bile flow without an effect on the temperature of the animal.3. The three mononitrophenols, the five remaining isomeric dinitrophenols, isopicramic acid, the aminonitrophenols, phenol, 2,4-dinitroanisole, 2,4-dinitrobenzoic acid, 2,4-dinitrobenzene sulphonic acid, 2,4-dinitroresorcinol and 4-nitracatechol had little effect on bile secretion or body temperature.4. It thus appears that, in order for a compound of this type to have a pronounced effect on bile secretion, it is necessary to have nitro groups in positions 2 and 4 of the benzene ring, and a free or potential hydroxyl group. 相似文献
99.
Limitations of the electrocardiographic response to exercise in predicting coronary-artery disease. 总被引:14,自引:0,他引:14
J S Borer J F Brensike D R Redwood S B Itscoitz E R Passamani N J Stone J M Richardson R I Levy S E Epstein 《The New England journal of medicine》1975,293(8):367-371
The electrocardiographic response to exercise was compared with the results of coronary angiography in 89 patients with Type II hyperlipoproteinemia who had previous myocardial infarction or typical angina or both (43 patients)(Group A), "atypical angina" (16 patients)(Group B)or positive electrocardiographic response to exercise without other evidence of cardiac disease (30 patients)(Group C). Thirty-nine of 43 in Group A had greater than or equal to 50 per cent stenosis, and 26 (67%) of these 39 had negative exercise tests. In Group B, five of the 16 had greater than or equal to 50% stenosis, and three had positive exercise tests (one patient had a false-positive test). In Group C, eleven of 30(37%) had greater than or equal to 50% stenosis; however, nine (30%) had minor stenosis (less than or equal to 50%), and 10(33%) normal coronary arteries. The diagnostic usefulness of exercise electrocardiography is limited. False-negative responses are frequent in patients with clinically suspected coronary disease, and false-positive responses frequent in asymptomatic patients. 相似文献
100.
Characterization of evolutionary rates and constraints in three Mammalian genomes 总被引:9,自引:3,他引:9 下载免费PDF全文
We present an analysis of rates and patterns of microevolutionary phenomena that have shaped the human, mouse, and rat genomes since their last common ancestor. We find evidence for a shift in the mutational spectrum between the mouse and rat lineages, with the net effect being a relative increase in GC content in the rat genome. Our estimate for the neutral point substitution rate separating the two rodents is 0.196 substitutions per site, and 0.65 substitutions per site for the tree relating all three mammals. Small insertions and deletions of 1-10 bp in length ("microindels") occur at approximately 5% of the point substitution rate. Inferred regional correlations in evolutionary rates between lineages and between types of sites support the idea that rates of evolution are influenced by local genomic or cell biological context. No substantial correlations between rates of point substitutions and rates of microindels are found, however, implying that the influences that affect these processes are distinct. Finally, we have identified those regions in the human genome that are evolving slowly, which are likely to include functional elements important to human biology. At least 5% of the human genome is under substantial constraint, most of which is noncoding. 相似文献