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281.
A. E. Schwint B. M. de Rey O. A. Bernaola R. Mazzei M. E. Itoiz 《Radiation and environmental biophysics》1989,28(2):121-130
Summary Rat tail epidermis was used to analyze the in vivo response of a biological system to heavy particle irradiation. The conical configuration of the rat tail gives rise to a variable energy degradation of the beam thus yielding information on the damage elicited by 2 different L.E.T. regions of the helium beam at different sites on the same sample. Cytochrome oxidase activity and epidermal thickness were used to analyze the metabolic and structural radioinduced response. Quantitative evaluation of radiation damage revealed marked variations within a few micrometers of tissue. 相似文献
282.
Summary A basic procedure was developed to produce high-protein amaranth flour (HPAF) using a commercial preparation of heat-stable alpha-amylase. Slurries (20%, w/v) of gelatinized whole flour were liquefied at 70 and 90°C, pH 6.5, 0.1% (w/v) enzyme concentration and 30 min hydrolysis time. Protein content of raw flour was increased from 15 to 29.6 or 39.3% at liquefaction temperatures of 70 or 90°C, respectively. Some physicochemical and functional properties of HPAF were assessed. HPAF might be used as a dry milk extender. 相似文献
283.
Karl H. Summer Dominik Klein Nada de Ruiter Josef Abel 《Biological trace element research》1989,21(1):165-169
In the present study we report on the effects of commonly used nonsteroidal antiinflammatory drugs on metallothionein (MT)
and MT-I mRNA levels. A single dose of chloroquine (100 mg/kg), diclofenac (100 mg/kg), indomethacin (10 mg/kg), or piroxicam
(100 mg/kg) was administered ip to C57B1 mice. After 18 h, MT levels were determined with a Cd-saturation radioassay. MT-I
mRNA levels were measured by Northern Blot analyses using a probe containing the mouse MT-I gene. All drugs tested caused
an increase in the MT content of the liver but not of the kidneys and lung. The lowest and highest effects were observed with
chloroquine (8 times the control value) and diclofenac (18 times), respectively. In accordance with the stimulation of MT
synthesis, increased accumulation of hepatic MT-I mRNA could be demonstrated.
These results indicate that elevated MT levels may contribute to the effectiveness of nonsteroidal antiinflammatory drugs
in the treatment of rheumatoid arthritis (RA). 相似文献
284.
J. A. L. van Kan M. D. van de Rhee D. Zuidema B. J. C. Cornelissen J. F. Bol 《Plant molecular biology》1989,12(2):153-155
Two tobacco genes encoding thaumatin-like proteins were cloned and sequenced. Both genes are expressed after infection of tobacco with tobacco mosaic virus (TMV). Comparison of the upstream sequences of these genes with those of other TMV-inducible tobacco genes revealed limited regions of homology. 相似文献
285.
Kees W. Rodenburg Marcel J. A. de Groot Rob A. Schilperoort Paul J. J. Hooykaas 《Plant molecular biology》1989,13(6):711-719
In relation to the question which DNA form (single- or double-stranded) is transferred by Agrobacterium tumefaciens to plant cells, we studied the behaviour of single-stranded DNA, as compared to double-stranded DNA, when it is introduced into plant protoplasts by electroporation. To this end, we cloned a construct with a plant NPTII gene as well as a CAT gene in the M13 vectors tg130 and tg131. We found that both complementary single-stranded molecules gave rise to substantial CAT activity in plant protoplasts, suggesting that single-stranded DNA is converted into double-stranded DNA by the plant cell replication machinery. Unexpectedly, we found that single-stranded DNA leads to a 3–10 fold higher frequency of stable transformation (selection for kanamycin resistance) than double-stranded DNA. These results indicate that the use of single-stranded DNA might be considered in experiments in which optimal transformation frequencies are needed, e.g. with protoplasts form recalcitrant plant species.Abbreviations ss
single-stranded
- ds
double-stranded
- CAT
chloramphenicol acetyl transferase
- NPTII
neomycin phosphotransferase II
- RT
room temperature 相似文献
286.
Gerd Gäde 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1989,159(5):589-596
Summary Extracts of corpora cardiaca from two members of the family Tenebrionidae,Zophobas rugipes andTenebrio molitor, from one member of the Chrysomelidae,Leptinotarsa decemlineata, and from three members of the Scarabaeidae,Pachnoda marginata, P. sinuata andMelolontha hippocastani, were assayed for adipokinetic and hypertrehalosaemic activity in acceptor locusts (Locusta migratoria) and cockroaches (Periplaneta americana), respectively. All corpus cardiacum material tested, except that from the cockchafer,M. hippocastani, gave positive bioassay results. Biological activities of corpus cardiacum extracts from all species investigated can be resolved on reversed-phase high performance liquid chromatography (RP-HPLC). Gland extracts from the two tenebrionid species each show a single peak of biological activity associated with a single peak of UV absorbance having an identical retention time in both species. The two biologically active fractions from the corpora cardiaca of the potato beetle,L. decemlineata, coelute with exogenous (synthetic) hypertrehalosaemic hormones I and II of the American cockroach. The two species of the genusPachnoda contain two active compounds in their glands; compound I of each species is more abundant and elutes just ahead of the (synthetic) hypertrehalosaemic hormone of the cockroachBlaberus discoidalis. The gland material ofM. hippocastani exhibits and absorbance peak with the same retention time as the major peak from thePachnoda-species; however, this peak material does not elicit biological activity in the assays used here. After fractionation by RP-HPLC the main biologically active compounds were subjected to amino acid analyses. All factors are peptidic and contain 8 amino acid residues. The peptides from the tenebrionid species have the amino acid residues Asx(2), Glx(1), Ser(1), Pro(1), Leu(1), Phe(1) and Trp(i), whereas the main peptide from corpora cardiaca ofP. marginata contains the residues Asx(2), Glx(1), Ser(1), Pro(1), Tyr(1), Leu(1) and Trp(1). Amino acid composition analyses of the two active fractions fromL. decemlineata reveal the residues Asx(2), Glx(1), Ser(1), Pro(1), Val(1), Phe(1) and Trp(1) for compound I and Asx(1), Glx(1), Thr(2), Pro(1), Leu(1), Phe(1) and Trp(1) for compound II. 相似文献
287.
288.
A. de Raucourt D. Girard Y. Prigent P. Boyaval 《Applied microbiology and biotechnology》1989,30(5):528-534
Summary An off-line parameter estimation method has been developed to predict the dynamic behaviour of a continuous lactose fermentation system. The model used is an unstructured model taking into account cell growth, substrate consumption, and metabolite production (lactic acid). This method, based on the Hooke-Jeeves non-linear-programming technique, results in a good estimation of the biological parameters of the model, and so gives a better understanding of the different phenomena involved in lactose fermentation.Nomenclature
Cp, Cs, Cz, Dp, Ds, Dz
coefficients in system (A)
-
Fe
bioreactor influent flow rate (1/h)
-
I
current in the ED unit (A)
-
J
lactate flux in the ED unit (g/h)
-
Kd
mortality constant (h-1)
-
Kp
product inhibition constant (g/l)
-
Ks
strbstrate saturation constant (g/l)
-
P
0
product concentration in the bioreactor (g/l)
-
P
1
product concentration in the D tank (g/l)
-
P
0r
estimation of P
0 (g/l)
-
Q
0
retentate flow rate (UF influent) (1/h)
-
Q
1
permeate flow rate (1/h)
-
Q
22
cell bleed flow rate (1/h)
-
Q
3
recycling flow rate in the ED (influent) (1/h)
-
Se
substrate concentration in the influent (g/l)
-
S
0
supstrate concentration in the bioreactor (g/l)
-
S
1
substrate concentration in tank D (g/l)
-
S
0r
estimation of S
0 (g/l)
-
t
time (h)
-
V
0
fermentation broth volume (1)
-
V
1
tank D volume (1)
-
X
0
biomass concentration in the bioreactor (g/l)
-
Y
P/S
(=1/Y
S/P) lactic acid yield coefficient (g lactic acid/g lactose consumed)
-
Y
X/S
(=1/Y
S/X) cell yield coefficient (g cells produced/g lactose consumed)
-
Y
X/Z
(=1/Y
Z/X) second cell yield coefficient (g cells produced/g nitrogen consumed)
-
Y
x, Y
m
input mathematical parameters of the linear system (M
2)
-
Ze
nitrogen concentration in the influent (g/l)
-
Z
0
nitrogen concentration in the bioreactor (g/l)
-
Z
1
nitrogen concentration in tank D (g/l)
-
Z
0r
estimation of Z
0 (g/l)
- ,
constants of the Luedeking and Piret's model
-
specific growth rate (h-1)
- max
maximum specific growth rate (h-1) 相似文献
289.
G. R. Zoutberg R. Willemsberg G. Smit M. J. Teixera de Mattos O. M. Neijssel 《Applied microbiology and biotechnology》1989,32(1):17-21
Summary
Clostridium butyricum was grown in a glucose-limited chemostat culture at a dilution rate of 0.1 h–1 at pH 6.0. With 0.9% w/v input glucose in the medium the cells were found to grow in suspension and glucose was fermented completely to acetate and butyrate. An increase in the input concentration of glucose resulted in increased concentrations of end-products, but not all extra glucose was consumed. It could be demonstrated that this was due to a lowering of the maximal growth rate by elevated levels of butyric acid. However, prolonged growth in the presence of high glucose concentrations led to an increase in biomass. This was caused by the selection of a variant that was less sensitive to butyrate. This variant was able to form aggregates in an anaerobic gas-lift reactor at high dilution rates. Inoculation of these aggregates in a conventional chemostat culture with high glucose input resulted in an aggregated culture that remained stable for at least 6 months, and in which all glucose was consumed. Whether the organisms grew in suspension or in aggregates was found to be determined by the concentration of butyrate. The isolation of aggregate-forming variants from chemostat cultures leads to a very simple and new type of immobilization technique.Offprint requests to: G. R. Zoutberg 相似文献
290.
L L Wheeless J S Coon C Cox A D Deitch R W de Vere White L G Koss M R Melamed M J O'Connell J E Reeder R S Weinstein 《Cytometry》1989,10(6):731-738
A Bladder Cancer Flow Cytometry Network study has been carried out aimed at identification of the sources of inter- and intralaboratory variability. Replicate "cocktail" samples containing a mixture of peripheral blood lymphocytes and an aneuploid cell line and samples of peripheral blood lymphocytes serving as a DNA reference standard were distributed to five network laboratories. The samples were stained for DNA using propidium iodide, with each laboratory using its own staining protocol. Sets of these samples were analyzed by flow cytometry to obtain cellular DNA distributions. DNA index and hyperdiploid fraction were calculated for each histogram using an automated technique. Results were evaluated by analysis of variance to identify sources of variability. Three important sources of variation were found that affect flow cytometry in general and- the transportability of flow cytometry results to routine clinical use in particular. The significant variation among laboratories that is constant across time most probably represents stable differences in instrumentation, instrument set-up, and laboratory techniques. This variation can be compensated for, if it is known and stable, to develop transportable classification criteria. The second type of variation, termed the interaction component, represents differences among laboratories that are not constant across time. Sources of this variation include inconsistency in sample preparation, staining, and analysis. The elimination of this type of variation is required for meaningful comparison of data within and among laboratories and the creation of interlaboratory data-bases. The third type of variation represents pure measurement variability and affects the sensitivity of the technique. 相似文献