全文获取类型
收费全文 | 39198篇 |
免费 | 2689篇 |
国内免费 | 69篇 |
专业分类
耳鼻咽喉 | 302篇 |
儿科学 | 975篇 |
妇产科学 | 839篇 |
基础医学 | 5448篇 |
口腔科学 | 1069篇 |
临床医学 | 4514篇 |
内科学 | 8366篇 |
皮肤病学 | 596篇 |
神经病学 | 3627篇 |
特种医学 | 1279篇 |
外科学 | 5347篇 |
综合类 | 199篇 |
一般理论 | 25篇 |
预防医学 | 3408篇 |
眼科学 | 485篇 |
药学 | 2821篇 |
中国医学 | 47篇 |
肿瘤学 | 2609篇 |
出版年
2023年 | 417篇 |
2022年 | 207篇 |
2021年 | 572篇 |
2020年 | 623篇 |
2019年 | 696篇 |
2018年 | 1187篇 |
2017年 | 1124篇 |
2016年 | 1154篇 |
2015年 | 966篇 |
2014年 | 1119篇 |
2013年 | 2068篇 |
2012年 | 2665篇 |
2011年 | 2858篇 |
2010年 | 1470篇 |
2009年 | 1213篇 |
2008年 | 2490篇 |
2007年 | 2518篇 |
2006年 | 2343篇 |
2005年 | 2226篇 |
2004年 | 1992篇 |
2003年 | 1891篇 |
2002年 | 1868篇 |
2001年 | 1022篇 |
2000年 | 1199篇 |
1999年 | 743篇 |
1998年 | 284篇 |
1997年 | 236篇 |
1996年 | 181篇 |
1995年 | 181篇 |
1994年 | 203篇 |
1993年 | 183篇 |
1992年 | 277篇 |
1991年 | 259篇 |
1990年 | 213篇 |
1989年 | 226篇 |
1988年 | 253篇 |
1987年 | 213篇 |
1986年 | 223篇 |
1985年 | 276篇 |
1984年 | 266篇 |
1983年 | 200篇 |
1982年 | 171篇 |
1981年 | 134篇 |
1980年 | 119篇 |
1979年 | 160篇 |
1978年 | 112篇 |
1977年 | 109篇 |
1976年 | 83篇 |
1975年 | 78篇 |
1973年 | 72篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
International comparisons show that populations having a high consumption of fish experience low incidence of breast cancer. We compared death rates from breast cancer among socioeconomic groups in a prospective study of 533,276 Norwegian women aged 35–54 years who were followed from 1970 through 1985. Compared with the reference group (wives of unskilled workers) the fishermen's wives had a decreased risk of breast cancer with a relative risk (RR) of 0.67 (95% confidence interval [CI]=0.47–0.94) adjusted for age and the number of children. Among fishermen's wives who were parous, adjustment for age at first birth gave an RR of 0.62 (CI=0.43–0.91). This study supports the hypothesis that certain aspects of diet, i. e., fish consumption, may be associated with lower breast-cancer mortality.Drs Lund and Bønaa are with the Institute of Community Medicine, University of Tromsø, Tromsø, Norway. Address correspondence to Dr Lund, Institute of Community Medicine, University of Tromsø, N-9037 Tromsø, Norway. 相似文献
32.
33.
34.
OBJECTIVE: The purpose of this study was to obtain information about how patients perceive the health care delivered in an emergency department. SETTING: Patients who visited the ED at a Swedish university hospital during the daytime on Monday through Friday during a four-week period and were expected to be discharged from the ED after their visit were included in the study. Other criteria for participation were the patients' mental and physical abilities to fill out a questionnaire. STUDY DESIGN: One hundred eighty-seven patients (110 women and 77 men) classified as orthopedic, gynecologic, internal medical, surgical, or neurologic patients evaluated their perception of the health care delivered in the ED by filling out a questionnaire after arrival and before discharge. MEASUREMENTS AND MAIN RESULTS: The perceptions of the care received were on average quite positive. This was supported indirectly by the fact that scored pain, strength, calmness, and despair changed in a positive direction during the ED stay. However, a pattern of varying satisfaction appeared when the patients were dichotomized into three groups according to how they had perceived their first information on arrival. Fourteen percent of the patients had received exact information, 20% were partly informed, and 66% had received no information about what was going to happen to them next. Those who received the most information at the time of arrival at the ED were more satisfied with the general treatment (P less than .05), respect (P less than .01), and attitude (P less than .05) later shown by the staff as well as with the information given later (P less than .05) than were the patients who had received no information at all on arrival. The general evaluation of the ED was more positively (P less than .001) scored by the patients who received the most information (they were more satisfied) compared with the other two groups. CONCLUSION: The information given to patients on arrival at the ED may be important to a positive perception of the care given during their stay. 相似文献
35.
Anders Bj?rkman Peter J?rgsholm 《Nordisk plastikkirurgisk forening [and] Nordisk klubb for handkirurgi》2004,38(1):32-35
Although rupture of the extensor pollicis longus (EPL) tendon is a well-known complication of distal radial fractures, a number of patients rupture the EPL because of other conditions. We have retrospectively studied the aetiology of 27 ruptures of the EPL in 26 consecutive patients. Of 19 patients with injured wrists 12 had distal radial fractures, five had blunt trauma, and two had stab wounds that resulted in rupture. In the radial fractures operated on, the EPL rupture was caused by chafing against a dorsal plate (n = 2) or wear against the pins of an external fixator (n = 2). Six patients were taking steroids for systemic diseases and in two cases a local steroid injection was given just before the rupture. We conclude that previous injury is the most common cause of rupture of the EPL. but that rheumatoid arthritis or local or systemic steroids, or both, are also important aetiological factors. Seven patients had an iatrogenic cause for their rupture. 相似文献
36.
The effect of various thermal processes on the glycemic response to whole grain wheat products in humans and rats 总被引:1,自引:0,他引:1
J Holm B Hagander I Bj?rck A C Eliasson I Lundquist 《The Journal of nutrition》1989,119(11):1631-1638
The effects of different thermal processes used to produce ready-to-eat cereals on the glycemic response to whole grain wheat were investigated in rats. The metabolic response to drum dried flour, which constitutes the major component in instant gruel and porridge, was also studied in healthy human subjects. Boiled flour was used for comparison. The degree of starch gelatinization and rate of starch hydrolysis in vitro were also measured. Incompletely gelatinized steam flaked and dry autoclaved products were digested more slowly in vitro and elicited lower glucose responses in rats compared with completely gelatinized drum dried, extrusion cooked or boiled samples. The initial glycemic response in rats was closely related to the rate of starch hydrolysis in the pepsin/alpha-amylase assay (r = 0.91, P less than 0.04). When pepsin was omitted, no significant correlation was obtained. The peak glucose, insulin and C-peptide responses in humans after breakfast meals of porridge prepared from drum dried flour and from boiled flour were similar, whereas the rate of depression of the glucose curve was more rapid after consuming drum dried porridge. It is concluded that the glycemic response to wheat products is affected by the processing conditions used. The more severe the processing conditions, the more rapid the digestion of starch. 相似文献
37.
H Bell A Bj?rneboe B Eidsvoll K R Norum N Raknerud K Try Y Thomassen C A Drevon 《Alcohol and alcoholism (Oxford, Oxfordshire)》1992,27(1):39-46
The concentration of alpha-tocopherol was measured in liver biopsy specimens obtained from 83 patients with alcoholic and non-alcoholic liver diseases. The mean hepatic vitamin E content (as alpha-tocopherol) was significantly lower in 23 patients with alcoholic cirrhosis (17.6 +/- 12.1 nmol/mg wet weight liver), compared with 12 patients with normal liver histology (39.2 +/- 29.7 nmol/mg, P less than 0.01). The mean serum concentration of alpha-tocopherol was lower in patients with alcoholic cirrhosis (13.9 +/- 7.0 mumol/l) than in individuals with alcoholic fatty liver (21.3 +/- 9.3 mumol/l, P less than 0.01) and patients with normal liver histology (23.4 +/- 11.6 mumol/l, P less than 0.01). A decreased ratio of serum alpha-tocopherol/total serum lipids was also observed in patients with alcoholic cirrhosis, compared with patients with normal liver histology (P less than 0.05). There was a significant correlation between concentrations of alpha-tocopherol in liver and serum (r = 0.43, P less than 0.001). Furthermore, serum alpha-tocopherol correlated with retinol (r = 0.53, P less than 0.001), selenium (r = 0.45, P less than 0.001), and albumin (r = 0.37, P less than 0.001) in serum. We suggest that the reduced content of hepatic alpha-tocopherol observed in some patients may play a role in ethanol-induced lipid peroxidation. 相似文献
38.
Effects of Clodronate on Cortical and Trabecular Bone in Ovariectomized Rats on a Low Calcium Diet 总被引:5,自引:0,他引:5
T. S. Kaastad O. Reikerås J. E. Madsen S. Narum J. H. Strømme K. J. Obrant L. Nordsletten 《Calcified tissue international》1997,61(2):158-164
The aim of this study was to evaluate the contribution of a low calcium diet to the cortical and trabecular osteoporosis
seen in ovariectomized rats after 7 weeks on a low calcium diet and to investigate the effects of the bisphosphonate clodronate
on this development of osteoporosis. Thirty-six mature, female Wistar rats were randomized into four groups: Ovx−B (bisphosphonate)
and Ovx−C (control) were ovariectomized, and Sham−Ca (low calcium) and Sham+Ca (normal calcium) were sham operated. The first
three groups were fed a low calcium diet (0.01%) and Sham+Ca normal rat chow (Ca 1.1%). The Ovx−B received 10 mg/kg s.c. clodronate
daily for nine weeks, and Ovx−C, Sham−Ca, and Sham+Ca received the same volumes of saline. Bone mineral turnover measured
as 85Sr-uptake was increased in all low calcium groups compared to Sham+Ca. The Sham+Ca femora had higher dry weight and ash weight
than the other groups, and Ovx−C had higher dry weight compared with Ovx−B and Sham−Ca. Calcium content was lower in both
Ovx groups compared to both Sham groups. Magnesium was lower in all groups compared to Sham+Ca and higher in Ovx−B compared
with Ovx−C. In the femoral shaft, Sham+Ca had significantly higher ultimate bending moment, energy absorption, and deflection
compared to the other three groups. Ultimate bending moment was higher in Sham−Ca than in Ovx−C. Stiffness was increased in
both Sham+Ca and Ovx−B compared to Ovx−C. The maximum stress in the femoral midshaft was higher in Sham+Ca than in the other
groups, and higher in Ovx−B than in Ovx−C. Histomorphometry showed increased medullary area in all low calcium groups compared
to Sham+Ca and larger cortical area in Sham+Ca and Ovx−B compared to Ovx−C. Compared to Sham+Ca the trabecular bone volume
was decreased to 30% in Sham−Ca and to 9% in Ovx−C, but was unchanged in Ovx−B. The low calcium diet generally increased bone
mineral turnover and reduced the tibial bone volume. Femoral changes led to a reduction of cortical fracture strength and
maximal stress. Ovariectomy in addition to a low calcium diet reduced femoral strength even more. Daily injections of clodronate
to ovariectomized rats on a low calcium diet increased femoral shaft stiffness and maximum stress, and clodronate preserved
both trabecular and cortical tibial bone volume completely.
Received: 11 June 1996 / Accepted: 5 March 1997 相似文献
39.
Hexokinase I (ATP:
-hexose 6-phosphotransferase, EC 2.7.1.1) is the first enzyme required in the metabolism of glucose in the central nervous system and plays a major role in regulation of the cerebral glycolytic rate. The distribution of hexokinase I mRNA was examined throughout the central nervous system of the rat by use of oligonucleotide probes and in situ hybridization histochemistry. In the rhinencephalon, strong hexokinase I mRNA labeling was demonstrated in the glomerular, mitral, internal granular, and internal plexiform layers, whereas the olfactory nerve, external plexiform, and subependymal layers and ependyma were devoid of labeling. Within the telencephalon, strong labeling was present in all layers (with the exception of the molecular layer) of the cerebral cortex, in the septum, in CA1-4 and dentate gyrus of the hippocampus, and in several amygdaloid nuclei. There was only weak labeling in the nucleus accumbens and caudate putamen. In the diencephalon, there was in general a strong labeling in the epithalamus, in several thalamic nuclei, including the anteriodorsal, anterioventral, anteriomedial, reticular, paravetricular, intermediodorsal, anteriomedial, interanteriomedial, rhomboid, reuniens, and parafascicular thalamic nuclei. Several hypothalamic regions, including the subfornical organ, the medial preoptic area, the suprachiasmatic, supraoptic, paraventricular, dorsomedial, ventromedial nuclei, and the zona incerta, were strongly labeled. In the mesencephalon, there was particularly strong labeling in the pars compacta and reticulata of the substantia nigra, central gray, and red nucleus, in the Darkschewitsch nucleus, and in the medial accessory oculomotor nucleus. In the rhombencephalon, there was strong hybridization in all raphe nuclei, pontine, tegmental, lateral parabrachial, olivary nuclei, and several cranial motor nuclei. All neurons of the locus ceruleus were heavily labeled. Very strong labeling was present in Purkinje and granular cells of the cerebellar cortex. Neurons of the medulla oblongata area postrema, nucleus tractus solitarius, reticular nucleus, nucleus cuneatus and several motor nuclei were strongly labeled. In the spinal cord, labeled cells were present in all laminae, and also neurons of the dorsal root ganglion were heavily labeled. Hexokinase I mRNA was also demonstrated in the epithelium lining the choroid plexus. In the E15 fetus, very strong labeling was seen in the liver, heart, and trigeminal ganglion, with less intense labeling in the brain and other tissues having more moderate labeling. Administration of 2% saline as drinking water resulted in a marked increase in hexokinase I mRNA in the magnocellular neurons of the supraoptic and paraventricular nuclei. In summary, the results show extensive neuronal distribution of hexokinase I mRNA with regional differences in the expression pattern. 相似文献
40.
The effects of the enantiomers of 5-fluoro-8-hydroxy-2-(dipropylamino)tetralin, UH-301 and the potent 5-HT1A-receptor agonist (R)-8-hydroxy-2-(dipropylamino)tetralin, (R)-8-OH-DPAT, on locomotion, rearing and total activity were studied in rats. The experiments were performed as tests either of exploratory activity in non-habituated rats or of motor activity of rats habituated to the environment for 2 h before drug injection. (R)-8-OH-DPAT increased locomotion and total activity and decreased rearing in both conditions. (R)-UH-301 increased locomotion and slightly also total activity in habituated rats and decreased rearing in both conditions. (S)-UH-301 decreased locomotion and rearing in both conditions but only in doses of 10 mumol/kg and above. Lower doses of (S)-UH-301 (10 mumol/kg) antagonized (R)-8-OH-DPAT-induced increases of locomotion and total activity. As (S)-UH-301 decreased rearing, per se, it was not able to antagonize the (R)-8-OH-DPAT induced decrease. These results further support previous data that (S)-UH-301 is a 5-HT1A antagonist while (R)-UH-301 is a 5-HT1A agonist. 相似文献