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排序方式: 共有1246条查询结果,搜索用时 15 毫秒
61.
Iester M Altieri M Michelson G Vittone P Calabria G Traverso CE 《Journal of glaucoma》2002,11(6):488-492
PURPOSE: To evaluate the intraobserver reproducibility of a software designed to assess retinal blood flow with the Heidelberg Retina Flowmeter (HRF). METHODS: Ten subjects were consecutively recruited, and one eye of each patient was randomly selected for study. Blood flow measurements were analyzed by using an automatic full field perfusion image analysis (AFFPIA) program, which calculates the Doppler frequency shift and hemodynamic variables (flow, volume, and velocity) for each pixel. The resulting perfusion image is processed with respect to underexposed and overexposed pixels, saccades, and retinal vessel tree. Intraobserver reproducibility was calculated for the AFFPIA program. All the optic nerve heads were horizontally divided into three sections (superior, central, and inferior). The retinal blood flow was calculated in the superior and inferior section, and each section was further divided into three areas (temporal, nasal, and rim). The blood flow was evaluated for each area. RESULTS: When the same observer analyzed the same image five times (intraobserver intraimage reproducibility), the AFFPIA coefficient of variation ranged from 0.5% to 5% in the temporal area, from 0.1% to 5.3% in the nasal area, and from 0.5 to 28% in the rim area.When the same observer analyzed three different images of the same section once (intraobserver interimage reproducibility), the AFFPIA coefficient of variation of flow measurements ranged from 1% to 7.3% in the temporal area, from 1.5% to 10% in the nasal area, and from 2 to 30% in the rim area. CONCLUSION: Retinal blood flow measured by HRF and analyzed by AFFPIA had good intraobserver reproducibility. The reproducibility was significantly better in the temporal and nasal areas than in the rim area. 相似文献
62.
The use of the simulation tool GEANT for neutron transport at energies below 20 MeV is discussed, in particular with regard to shielding and dose calculations. The reliability of the GEANT/MICAP package for neutron transport in a wide energy range has been verified by comparing the results of simulations performed with this package in a wide energy range with the prediction of MCNP-4B, a code commonly used for neutron transport at low energy. A reasonable agreement between the results of the two codes is found for the neutron flux through a slab of material (iron and ordinary concrete), as well as for the dose released in soft tissue by neutrons. These results justify the use of the GEANT/MICAP code for neutron transport in a wide range of applications, including health physics problems. 相似文献
63.
Do transient ischemic attacks have a neuroprotective effect? 总被引:82,自引:0,他引:82
OBJECTIVE: To determine whether TIAs have a neuroprotective effect. BACKGROUND: Ischemic tolerance or preconditioning, which protects the brain against stroke, has been demonstrated in animal models of cerebral ischemia. Because TIA may represent a clinical model of ischemic tolerance, patients with TIA before cerebral infarction (CI) may therefore have a better outcome than patients without TIA before CI. METHODS: A total of 2,490 patients admitted consecutively to a primary care center for first-ever CI in the anterior circulation were divided into two groups on the basis of the presence or absence of prior ipsilateral TIAs. Duration of TIA was classified into three groups (<10 minutes, 10 to 20 minutes, and >20 minutes). The severity of the neurologic picture on admission and functional disability after stroke were compared between patients with and without TIAs. RESULTS: A total of 293 (12%) of the 2,490 patients had prior ipsilateral TIAs before CI. Risk factors did not differ between patients with or without TIAs, whereas the topography and etiology of ischemic stroke did differ (p < 0.001). Patients without prior TIAs had a more severe clinical picture on admission, with a greater reduction of consciousness (p = 0.009). Patients with previous TIAs had a more favorable outcome than those without TIAs (67% versus 58%, p = 0.004). After adjustment for confounding variables, TIAs lasting 10 to 20 minutes were still associated with a favorable outcome (odds ratio, 1.98; 95% confidence interval, 1.27 to 3.08; p = 0.002). The interval between TIA and CI influenced the outcome (p = 0.007). CONCLUSIONS: This study suggests that ischemic tolerance may play a role in patients with ipsilateral TIAs before CI, allowing better recovery from a subsequent ischemic stroke. 相似文献
64.
Loss of tumor-promoting activity of unleaded gasoline in N- nitrosodiethylamine-initiated ovariectomized B6C3F1 mouse liver 总被引:1,自引:0,他引:1
Unleaded gasoline (UG) vapor (2056 ppm) increased the incidence of liver
tumors in a chronic bioassay and exhibited tumor-promoting activity in
N-nitrosodiethylamine (DEN)-initiated female mouse liver. Estrogen
inhibited mouse liver tumor development and the hepatocarcinogenic and
tumor-promoting dose of UG produced uterine changes suggestive of estrogen
antagonism. To directly test the hypothesis that UG-induced tumor-promoting
ability is secondary to its interaction with the mouse liver tumor
inhibitor, estrogen, we compared the tumor-promoting ability of UG in
ovariectomized (Ovex) mice with the hepatic tumor-promoting ability of UG
in intact mice. Ovaries were surgically removed at 4 weeks of age. Exposure
to wholly vaporized UG (2018 ppm) under bioassay and tumor-promoting
conditions began at 8 weeks of age. After 4 months of exposure, UG
increased relative liver weight and hepatic microsomal cytochrome P450
pentoxyresourfin-O- dealkylase and ethoxyresorufin-O-deethylase activity to
a similar extent in intact and Ovex mice. Non-focal hepatocyte
proliferation, as measured by the incorporation of bromo-deoxyuridine, was
not changed by UG exposure and was similar in all treatment groups. After 4
months of exposure to DEN-initiated mice, UG significantly increased the
volume fraction of liver occupied by foci (three-fold) as compared to
control intact mice. As expected, volume of foci was elevated in
DEN/Ovex/control mice as compared to DEN/intact/control mice. In DEN/Ovex
mice UG did not significantly increase the focal volume fraction. Thus, the
tumor promoting activity of UG, as demonstrated by increased volume
fraction of liver occupied by hepatic foci in intact mice, is greatly
attenuated in Ovex mice. The volume fraction data in Ovex mice support the
hypothesis that the tumor promoting activity of UG is dependent upon the
interaction of UG with ovarian hormones. These data also indicate that
hepatic microsomal cytochrome P450 PROD and EROD induction, hepatomegaly
and non-focal hepatic LI are not specific markers of hepatic tumor
promoting activity of UG.
相似文献
65.
Perkins SN; Hursting SD; Haines DC; James SJ; Miller BJ; Phang JM 《Carcinogenesis》1997,18(5):989-994
Transgenic mice with both alleles of the p53 tumor suppressor gene product
'knocked out' by gene targeting are susceptible to early development of
tumors, chiefly lymphomas and sarcomas. Compared with the control group,
administration of dehydroepiandrosterone (DHEA) at 0.3% of the diet to male
p53-deficient mice extended their lifespan by delaying death due to
neoplasms (from 105 to 166 days on study, P = 0.002), primarily by
suppressing lymphoblastic lymphoma (from 45 to 6% of neoplastic deaths, P =
0.010). Treatment with a synthetic DHEA analog,
16alpha-fluoro-5-androsten-17-one (compound 8354), at 0.15% of the diet
also increased lifespan, to 140 days for mice that developed tumors (P =
0.037). The effects of these steroids on lifespan and tumor development did
not appear to be strongly related to inhibition of food consumption and
weight gain, in that a group pair-fed with control diet to the reduced food
consumption of the DHEA-treated group developed and died of the same types
of neoplasms at the same rate as the controls fed ad libitum. The
chemopreventive effect of these steroids has been proposed to be due to
suppression of DNA synthesis by inhibition of glucose 6-phosphate
dehydrogenase, the rate-limiting enzyme of the pentose phosphate pathway.
Although DHEA and its analog are strong non- competitive inhibitors of this
enzyme in vitro, treatment with DHEA did not deplete cellular nucleotide
pools in the liver, as would have been predicted. The chemopreventive
effect of DHEA in this model may be due to steroid-induced thymic atrophy
and suppression of T cell lymphoma, permitting these mice to survive long
enough to develop tumors with longer latency.
相似文献
66.
Wu DC; Liu JM; Chen YM; Yang S; Liu SM; Chen LT; Whang-Peng J 《Japanese journal of clinical oncology》1997,27(2):115-118
Hemolytic uremic syndrome spontaneously arises in a few patients with
advanced cancer, but it is more commonly related to the use of certain
chemotherapeutic agents. Mitomycin-C is, etiologically, the most common
causative agent inducing hemolytic uremic syndrome, in a dose dependent
manner. We report this syndrome, attributable to mitomycin-C at a
cumulative dose of 40 mg/m2, in a gastric cancer patient. A 42-year-old
female with stage III gastric cancer underwent radical gastrectomy and was
given mitomycin-C at 10 mg/m2 intravenously every four weeks as adjuvant
therapy. Hemolytic uremic syndrome was diagnosed three months after the
last dose of mitomycin-C administration. The most prominent symptoms
included pallor, hypertension and anasarca, with laboratory evidence of
microangiopathic hemolytic anemia, azotemia and hyperkalemia. Her disease
was progressive, but fortunately stabilized after staphylococcus column A
dialysis. Her disease remained in remission for 24 months from the time of
diagnosis, and then relapsed in the form of peritoneal carcinomatosis with
partial intestinal obstruction.
相似文献
67.
MM Harjai DC Agarwal P Dave SS Jog P Arora SM VSM 《Medical Journal Armed Forces India》2005,61(2):143-147
Background
The sudden increase in incidence and magnitude of mine blast injuries prompted us to highlight the problem and its management.Methods
The cases of mine blast injuries occurring during mining and demining in a particular geographical area were analysed. Total 27 cases of mine blast injuries occurred during mining or demining operations in a period of 13 months.Results
Various body regions were involved in the mine blast injuries but the main brunt was borne by feet and legs followed by multiple body regions due to splinters. 14 patients underwent below knee (BK) amputation while 4 patients required through knee (TK) amputations. The effect of blast was so severe that most of the cases required 2 to 5 times wound debridements. The initial aggressive debridement / open stump amputation saved the limb and life of all patients.Conclusion
A mine blast causes extensive injuries and psychological trauma. Management is needed urgently, surgery is difficult, and amputation is often inevitable. Maximum lives and limbs can be saved with aggressive debridement, repeated inspections and dressings under anaesthesia and definitive closure at optimum time.Key Words: Amputation, Antipersonnel mine, Crush syndrome, Debridements, Mine blast injury, Secondary missiles, Shrapenels 相似文献68.
69.
70.
Altieri P Devoto E Spallarossa P Rossettin P Garibaldi S Bertero G Balbi M Barsotti A Brunelli C Ghigliotti G 《Thrombosis research》2005,115(1-2):65-72
BACKGROUND: Coagulation FXII is activated on contact with lipoprotein particles. It has been suggested that contact with subendothelial tissue provides an alternative biological surface for FXII activation. Our aim was to investigate whether activated FXII (FXIIa) is elevated in patients with coronary atherosclerosis, and whether disease status (acute phase or stable state) affects circulating levels of FXIIa. METHODS: Circulating FXIIa levels were measured in the peripheral blood of 122 patients with coronary atherosclerosis (32, stable angina; 54, unstable angina; 36, nQ myocardial infarction) and in 45 age-matched subjects (Contr). RESULTS: FXIIa levels (median, first and third quartiles; ng/ml) were higher in patients than in Contr: 1.61 (1.26-2.02) vs. 1.34 (1.13-1.81) (p<0.01). FXIIa levels were similar among patients with stable angina [1.66 (1.23-1.91)], unstable angina [1.53 (1.21-2.04)], and nQ myocardial infarction [1.75 (1.34-2.03)]. The three groups of patients had similar prevalence for most atherothrombotic risk factors; patients with stable angina had an increased severity of coronary disease, which did not explain the different levels of FXIIa. Fasting levels of triglycerides were the best predictor of FXIIa levels in our patients. CONCLUSIONS: The finding of similar FXIIa levels among patients in either acute or chronic phases of coronary atherosclerosis suggests that the initial arterial denudation and the acute-phase response associated to acute coronary syndromes are not major determinants for prolonged FXII activation. 相似文献