全文获取类型
收费全文 | 8846篇 |
免费 | 536篇 |
国内免费 | 86篇 |
专业分类
耳鼻咽喉 | 65篇 |
儿科学 | 277篇 |
妇产科学 | 200篇 |
基础医学 | 1370篇 |
口腔科学 | 508篇 |
临床医学 | 1032篇 |
内科学 | 1569篇 |
皮肤病学 | 154篇 |
神经病学 | 777篇 |
特种医学 | 304篇 |
外国民族医学 | 2篇 |
外科学 | 1012篇 |
综合类 | 72篇 |
一般理论 | 3篇 |
预防医学 | 744篇 |
眼科学 | 84篇 |
药学 | 720篇 |
中国医学 | 25篇 |
肿瘤学 | 550篇 |
出版年
2022年 | 73篇 |
2021年 | 118篇 |
2020年 | 94篇 |
2019年 | 144篇 |
2018年 | 151篇 |
2017年 | 133篇 |
2016年 | 130篇 |
2015年 | 116篇 |
2014年 | 198篇 |
2013年 | 323篇 |
2012年 | 409篇 |
2011年 | 421篇 |
2010年 | 226篇 |
2009年 | 234篇 |
2008年 | 387篇 |
2007年 | 369篇 |
2006年 | 368篇 |
2005年 | 366篇 |
2004年 | 315篇 |
2003年 | 268篇 |
2002年 | 299篇 |
2001年 | 261篇 |
2000年 | 284篇 |
1999年 | 264篇 |
1998年 | 110篇 |
1997年 | 115篇 |
1996年 | 85篇 |
1995年 | 97篇 |
1994年 | 81篇 |
1993年 | 76篇 |
1992年 | 184篇 |
1991年 | 206篇 |
1990年 | 200篇 |
1989年 | 192篇 |
1988年 | 196篇 |
1987年 | 198篇 |
1986年 | 193篇 |
1985年 | 191篇 |
1984年 | 109篇 |
1983年 | 124篇 |
1982年 | 84篇 |
1981年 | 83篇 |
1980年 | 65篇 |
1979年 | 106篇 |
1978年 | 97篇 |
1977年 | 85篇 |
1976年 | 61篇 |
1975年 | 67篇 |
1974年 | 59篇 |
1973年 | 53篇 |
排序方式: 共有9468条查询结果,搜索用时 15 毫秒
31.
D J Stennett W H Gerwick P K Egging J M Christensen 《JPEN. Journal of parenteral and enteral nutrition》1988,12(1):88-92
The composition of a precipitate obtained from a silastic right atrial catheter was determined. The precipitate was collected and washed with deionized water thoroughly before subjecting portions of it to organic and inorganic analysis. Inorganic analysis was conducted using scanning electron microscopy and x-ray spectroscopy for sodium, aluminum, silicone, sulfur, chlorine, and calcium. Phosphorus analysis was conducted by a commercial laboratory. Organic analysis was conducted by thin layer chromatography with cholesterol, phosphatidyl serine, phosphatidyl choline, phosphatidyl ethanolamine, and sphingomyelin as standards. Silicone, calcium, and phosphorus and three organic compounds, which could not be conclusively identified, were found. The precipitate was most likely calcium phosphate intermixed with silicone oil lubricant and residual total parenteral nutrition (TPN) solution. This formed in the catheter at body temperature probably due to incomplete catheter flushing. 相似文献
32.
The pattern of fluctuation in the population size of Bulinus globosus and Biomphalaria pfeifferi, in their infection rates with Schistosoma haematobium/S. mattheei and S. mansoni, respectively, and in the cercarial population size as monitored using hamster immersions, was elucidated in streams in the temperate highveld region of Zimbabwe over a 27-month period during 1982-1984. The results revealed that transmission of S. mansoni was erratic and unpredictable without a clearcut seasonal transmission pattern. In contrast, transmission of S. haematobium and S. mattheei exhibited a marked seasonal pattern, being most intensive during the hot, dry season (September-November) and markedly reduced during the cold, dry season (June-August). During the rainy (December-February) and warm, post-rainy (March-May) seasons transmission was moderate and variable, but occasionally intensive. The results also showed that rodent immersion is to be preferred to measurements of snail population size and snail infection rate in elucidating seasonality of transmission of schistosomiasis. 相似文献
33.
Unscheduled DNA synthesis (UDS) was studied by quantitative autoradiography in human urothelial cells of three transformation grades (TGr I-III). Cells incubated in arginine-free medium supplemented with hydroxyurea showed dose-dependent UDS after administration of agents injurious to DNA, while the scheduled synthesis of DNA was nearly totally suppressed. UDS was demonstrated after treatment with the ultimate carcinogen N-methyl-N-nitroso-N'-nitroguanidine (CAS: 70-25-7) or with the procarcinogen 4-nitroquinoline-1-oxide (4-NQO; CAS: 56-57-5). In cultures treated with benzo[a]pyrene (CAS: 50-32-8), which requires a different activation system than that for 4-NQO, UDS was less pronounced. In 9 cell lines the average rates of UDS were inversely related to TGr. Two cell lines showed a different pattern. 相似文献
34.
Intrinsic nerves in the mammalian colon: confirmation of a plexus at the circular muscle-submucosal interface 总被引:1,自引:0,他引:1
Slow waves in the small intestine seem to arise in plexuses of neurites with interstitial cells of Cajal. In the colon, slow waves appear to arise at the circular muscle - submucosal interface. We therefore sought a plexus at this surface in the colon in the cat, dog, ferret, opossum, rabbit, rat, guinea-pig and man. Segments from all levels of the colon were stained by the Champy-Maillet osmic acid-zinc iodide method and cut into serial 25 micron sections in the plane of the muscle layers. A dense network of neurites with abundant interstitial cells of Cajal was found at the circular muscle - submucosal interface in all species except rabbit. Neurites in this plexus appeared to arise from the deep plexus of the submucosa (Schabadasch's or Henle's plexus). It was not found in the small intestine and stomach. A similar plexus was found in the interstices of the myenteric plexus in the colon. Interstitial cells of Cajal in both plexuses were positive for the NADH-diaphorase stain, but not for silver impregnation. The possible roles of the plexuses of neurites and interstitial cells of Cajal at the circular muscle - submucosal interface and at the plane of the myenteric plexus in the generation of rhythmic activity in the colon are discussed. 相似文献
35.
Audiotape recordings of family interaction samples from 30 nondistressed and 32 multiproblem families were coded for communication deviance (CD). Maternal CD was found to be higher in families high on measures of "preschizophrenic" child behavior, externalizing or "acting out" offspring behavior, overall family distress, and maladaptive marital and family alliance structures. Paternal CD was found to be higher in families in which offspring were rated high on externalizing behaviors. 相似文献
36.
A. Gjerris F. Gjerris P. Soelberg Sørensen E. B. Sørensen N. J. Christensen J. Fahrenkrug J. F. Rehfeld 《Acta neurochirurgica》1988,91(1-2):55-59
Summary CSF concentrations of vasoactive intestinal polypeptide (VIP), cholecystokinin (CCK), noradrenaline (NA) and dopamine (DA) were measured in the lateral ventricles and at the lumbar level in patients with normal pressure hydrocephalus (NPH). The concentrations of VIP (n=15), NA (n=10) and DA (n=10) were significantly higher at the lumbar level than at the ventricular level, whereas the concentrations of CCK (n=9) were similar at the two sites. A signifikant positive correlation between the concentrations measured at the two levels was found for VIP (rs=0.65; p0.01) and DA (rs=0.94; p0.001). The results indicate that the concentrations of transmitter substances measured in CSF at the lumbar level not necessarily are indicative for concentrations measured more centrally. The negative correlations between Evans ratio and L-CSF VIP (rs=-0.76; p 0.001), and between resistance to outflow and V-CSF as well as L-CSF CCK (rs=-0.75); p 0.05) might be explained by a reduction in number of cortical neurons or by disturbances in CSF dynamics in patients with NPH. 相似文献
37.
Ove Christensen Marek Simon Torben Randlev 《Pflügers Archiv : European journal of physiology》1990,415(1):37-46
We have used the patch-clamp technique to characterize three anion channels in the ventricular membrane of the choroid plexus epithelium from Necturus. The most frequently occurring channel had a nonlinear IV-curve. The conductance in excised patches with 112 mM chloride at both sides was 28 pS at 0 mV, increasing towards positive membrane potentials. The selectivity ratios were P
NaP
Cl 0.1 and
. SITS and furosemide (1 mM) on the inside reduces chloride flux to 0.15 and 0.37 times the control value. In attached patches, the most commonly observed channel had a conductance of 7.5 pS. The single-channel current for this channel reversed direction at 15 mV hyperpolarization, indicating accumulation of chloride to a factor of 1.8 above equilibrium. External stimulation of the tissue by theophylline, IBMX and dbcAMP, or by hypotonic shock did not increase the activity of this channel. In very few excised patches, we have observed a chloride channel with a conductance of 7 pS with 112 mM chloride at both sides. The 7 pS channel appears to be identical to a 2 pS channel found in attached patches. The 2 pS channel was not normally active in attached patches but was activated in 28% of the patches by external stimulation. Finally, in few excised patches we have found a 375 pS channel which inactivates within seconds when membrane potential is stepped from 0 mV to a value that differs more than 10–20 mV from zero. The channel did not conduct gluconate but
and P
NaP
Cl 0.1. Internal SITS and furosemide (1 mM) reduced chloride flux to 0.3 and 0.5 times the control value. The channel was never seen in attached patches. The current carried through these channels can not account for the transepithelial steady state Cl–-flux measured by microelectrodes. KCl exit from the cell is suggested to be carried by KCl-cotransport or by channels that are too small to be seen in patch-clamp experiments. 相似文献
38.
By means of a questionnaire sent to all medical units in Malm?, including primary care, homes for the elderly, and industrial health clinics, 275 patients with leg and foot ulcers were identified. With a population of 232,908 in Malm?, this corresponds to a prevalence of 0.12%, which is lower than reported by others. Since the response rate was high (88% total, Primary Care: 100%), the prevalence of 0.12% is, however, believed to be real and might be explained by the urban area investigated, with easy access to care and proximity to one somatic hospital. 50% of the patients with leg and foot ulcers were treated in Primary Care, and 30% of the leg ulcer patients were treated at the Department of Dermatology. 88% of leg and foot ulcer patients were over 75 years of age. Median age was 79.5 years, with 80 for women and 76.5 for men. In Primary Care the median age was 82. There was a predominance of women in the study population with an overall sex ratio of 3:1. A higher proportion of patients living alone was found in Primary Care. The etiology of the ulcers was considered to be "unknown" or "other" or else no statement was given in 36% of the leg ulcer- and 22% of the foot ulcer patients. This might reflect an overall uncertainty about the underlying etiological cause. Medially and laterally located leg ulcers were reported equally often, but there was also a great proportion of wholly or partially circumferential ulcers. 76% of the foot ulcers were located on the toes.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
39.
In a double-blind crossover study, 12 depressed inpatients receiving bilateral electroconvulsive therapy (ECT) were given 22.5 mg oxazepam or placebo (identical tablets, randomized order) the night before treatment. Seizure duration was measured using the cuff method and a total of 20 pairs of measurements were made. Mean duration after oxazepam administration was 0.9 s longer than after placebo; this difference was not statistically significant. The relevant lower one-sided 95% confidence limit was -4.1 s. Single administration of oxazepam, 22.5 mg, has little average effect on seizure duration in ECT. 相似文献
40.